Main reasons
Arcing at wafer or chamber wall Arcing is an electrical breakdown due to:
  • Electrical charging of insulated surfaces (resist on the wafer or byproducts at the chamber wall) or
  • Insufficient grounded chamber parts
Arcing is an electrical discharge and results in localized heating and destruction of the dielectric materials.
Particles are negatively charged and injected into the plasma bulk. Due to the balance of electrical force and gravity, they remain at the border of plasma sheath and plasma bulk.

Likely, they will fall onto the wafer surface when the plasma is turned off.

For more details, please refer to the Plasmetrex' "Plasma School for Semiconductor Manufacturing."

Flaking at chamber wall

The build-up of byproducts at the chamber wall leads to flaking if the layers become too thick. In particular, a magnetic field can cause a large non-uniformity of the polymer build-up and flaking.
CF4 etch chemistry in a chamber with a ceramic dome can cause AlF3 particle generation.
Particle generation is increased by:
  •  Film stress through alternating films at the chamber wall
    • in case of process mix or
    • too thick films,
  • Mechanical stress such as vibration and wafer handling
Chemical reactions in plasma bulk The generation of particles is a result of unwanted chemical vapor reactions in the plasma bulk, at the chamber wall, and at the wafer. It depends on chemistry (CF4, Cl, or HBr).
  • Humidity in the CVD oxide process (caused by leaks) leads to particle generation from the vapor phase (homogeneous reaction).