Extended Defects in c-Si

General Perspective
Materials Science in Semiconductor Processing (MSSP)
Exact type of the predominant defects dependent on ion dose, energy and annealing conditions
Evolution (nucleation, growing, transforming, dissolving) upon annealing

In the case of Non-amorphizing Implants
{113} rod-like defects; {113} planes elongated along the <110> directions
Formation energy; 1-1.3 eV and slowly decreasing as the size of the defect increases
Defects growing in size and decrease in density upon annealing
Activation energy (3.7 eV) = binding energy + migration energy

Terms
Weak Beam Dark Field (WBDF) image
High-Resolution TEM (HREM)
Bravais lattices: 14 different point lattices
Point lattice + atom group = periodic atom array
Burgers vector: the shortest lattice translation vector of the crystalline structure

{113} Defects

{113} Defects
(800℃ of a 40 keV, 5x1013 Si+)

{113} Defects upon Annealing

Energies

Energies
Formation energy of a defect: energy incease due to the incorporation of an extra Si atom into a defect
Activation energy for the dissolution of the defects = activation energy for self-diffusion – formation of the defect =binding energy + migration energy

In the case of Medium-dose Implants
100 keV Si+–implanted Si at 800 ℃
{113} and dislocation loops (DL) coexist after 5 min annealing at 800 ℃
{113} defects are the source of DLs
Perfect dislocation loops (PDLs) and faulted dislocation loops (FDLs)

Medium-dose Implants

In the case of Amorphizing Implants
Oswald ripening process; formation energy decreases as its size increases and the supersaturation of Si’s around a large defect is smaller than around a small defect
Loop density varies with 1/t and the mean radius increases with t1/2
Wafer surface can be a better sink: when the free surface of the wafer is put closer a faster dissolution of PDL’s is observed but the emitted Si’s are not trapped by the FDL’s.

Amorphizing Implants
Formation energy of PDLs higher than FDLs
For low-budget thermal annealings, clusters and {113} defects coexist and the latter become predominant when increasing the annealing time
For higher thermal budgets, dislocation loops of two types are also found among the defects
For the highest temperatures only faulted dislocation loops survive

Amorphizing Implants

Amorphizing Implants

Thermal Evolution of FDLs

Competition between PDLs and FDLs

Origin of {113} Defects

Defect Evolution
Di-interstitials
{113} defects
PDLs and FDLs
FDLs
Surface effect as a sink

Defect Evolution
Driving force for the growth of a given type of defects is due to the decrease of the formation energy as its size increases
The change from one type of defect to the next is driven by the reduction of the formation energy consecutive to the crystallographical reordering of the same number of Si atoms into the new defect
Formation energy change due to the size increase or in their structural characteristics