Dislocation sink annihilating threading dislocations in strain-relaxed Si_1-x Ge _x layer.

Area of Science:

• Semiconductor Physics
• Materials Science
• Nanotechnology

Background:

• Advanced transistor designs, such as those beyond the 5nm node, require nearly crystalline-defect-free channels.
• Silicon-Germanium (SiGe) alloys are promising for next-generation transistors but often contain crystalline defects like dislocations.
• Misfit and threading dislocations degrade device performance and limit scaling.

Purpose of the Study:

• To propose and demonstrate a novel dislocation sink technology for creating defect-free SiGe channels.
• To enable the fabrication of SiGe multi-bridge-channel field-effect transistors (MBCFETs) that meet stringent design rules (beyond 5nm).
• To investigate the mechanisms and efficiency of dislocation annihilation in SiGe layers.

Main Methods:

• A dislocation sink was generated in a strain-relaxed Si0.7Ge0.3 layer using H+ implantation.
• Subsequent thermal annealing was performed to annihilate misfit and threading dislocations.
• Real-time in situ high-resolution transmission electron microscopy (HR-TEM) at 1.25 MV was used to observe the dislocation annihilation process.

Main Results:

• The dislocation sink technology effectively annihilated misfit and threading dislocations near the Si/SiGe interface.
• The annihilation process, identified as [Si interstitial or Ge interstitial + Si vacancy or Ge vacancy → SiGe], was directly observed.
• Maximum annihilation efficiency was achieved with H+ implantation dose of 5 × 10^15 atoms cm^-2 and annealing at 800 °C.

Conclusions:

• The proposed dislocation sink technology is effective in creating near-defect-free SiGe channels for advanced transistors.
• The H+ implantation and annealing process provides a viable method for defect reduction in SiGe layers.
• This technology is critical for realizing SiGe MBCFETs beyond the 5nm transistor design rule.