ANNEALING

• How: consists in heating the wafer (has three steps: raising temperature, plateau, decreasing the temperature)
  • temperature can be as low as 200oC or as high as 1000oC
• Purpose:
  • Repairing the damaged lattice (due to stress, implantation, etc)
  • Activate the dopant (in substitutional sites of the lattice) See picture below.

• Disadvantages:
  • The dopant profile is modified (dopants diffuse more than it is desired during the high temperature annealing) - see picture below
    • very bad for small devices
  • Reactions between metal and silicon at high temperature (Al-Si interdiffusion)