Species and dose dependence of ion implantation damage induced transient enhanced diffusion

AbstractThe interaction between boron and excess silicon interstitials caused by ion implantation hinders the formation of ultra-shallow, low resistivity junctions. Previous studies have shown that fluorine reduces boron transient enhanced diffusion, however it is unclear whether this observed phenomenon is due to the fluorine interacting with the boron atoms or silicon self-interstitials. Amorphization of a n-type Czochralski wafer was achieved with a 70 keV Si+ implantation at a dose of 1×1015/cm2. The Si+ implant produced a 1500Å deep amorphous layer, which was then implanted with 1.12 keV 1×1015/cm2 B+. The samples were then implanted with a dose of 2×1015/cm2F+ at various energies ranging from 2 keV to 36 keV. Ellipsometry measurements showed no increase in the amorphous layer thickness from either the boron or fluorine implants. The experimental conditions allowed the chemical species effect to be studied independent of the implant damage caused by the fluorine implant. Post-implantation anneals were performed in a tube furnace at 750° C. Secondary ion mass spectrometry was used to monitor the dopant diffusion after annealing. Transmission electron microscopy (TEM) was used to study the end-of-range defect evolution. The addition of fluorine reduces the boron transient enhanced diffusion for all fluorine energies. It was observed that both the magnitude of the boron diffusivity and the concentration gradient of the boron profile vary as a function of fluorine energy.

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A Historical View of the Role of Ion-Implantation Defects in PN Junction Formation for Devices

MRS Proceedings ◽

10.1557/proc-610-b4.1 ◽

2000 ◽

Vol 610 ◽

Cited By ~ 1

Author(s):

R.B. Fair

Keyword(s):

Ion Implantation ◽

Group Iii ◽

Enhanced Diffusion ◽

Historical View ◽

Implantation Damage ◽

Long Time ◽

Ultra Shallow Junctions ◽

Induced Defects ◽

Cs Ions

AbstractThe early use of ion bombardment of semiconductors for forming doped regions was viewed as a room-temperature process by solid-state scientists. Many interesting, but relatively useless devices were made by implanting species such as Na and Cs ions to form pn junctions from radiation damage or interstitial impurities. The revolutionary idea that one could implant Group III and V dopants into semiconductors and then heat the implanted substrate to above 800C didn't appear until 10 years after Shockley's 1954 patent. At that time, implantation damage became relatively unimportant as processes evolved with high temperature, long time diffusions. With the advent of rapid thermal processing, the attention shifted back to implantation-induced defects to explain transient-enhanced-diffusion effects. Today's challenges in forming ultra-shallow junctions by ion-implantation are in controlling and minimizing the damage structures that dominate junction activation and diffusion. Low-energy implants have been effective in this regard.

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