Major Categories of Silicon Chemical Vapor Deposition (CVD) (Table 6)

Parameters

• Pressure - Atmospheric or low pressure (LPCVD)
• Temperature - 500-1100° C
• Silicon and nitride sources - Silane (SiH₄), Silicon Tetrachloride (SiCl₄), Ammonia (NH₃), Nitrous Oxide (N₂O)
• Dopant sources - Arsine (AsH₃), Phosphine (PH₃), Diborane (B₂H₆)
• Carrier gases - Nitrogen (N₂), Hydrogen (H₂)
• Heating source -
  • Cold wall system - Radio frequency (RF) or Infrared (IR)
  • Hot wall system - thermal resistance

CVD Type

1. Medium temperature (~ 600-1100°C)
   1. Silicon Nitride (Si₃N₄)

      3 SiH₄ + 4 NH₃ —> Si₃N₄ + 12 H₂

      H₂ carrier gas (900-1100°C)

   2. Poly Silicon (Poly Si)

      SiH₄ + Heat —> Si + 2 H₂

      H₂ carrier gas (850-1000°C)

      N₂ carrier gas (600-700°C)

   3. Silicon Dioxide (SiO₂)
      1. SiH₄ + 4 CO₂ —> SiO₂ + 4 CO + 2 H₂O

         N₂ carrier gas (500-900°C)

      2. 2 H₂ + SiCl₄ + CO₂ —> SiO₂ + 4 HCl ^*

         H₂ carrier gas (800-1000°C)

      3. SiH₄ + CO —> SiO₂ + 2 H₂ ^*

         H₂ Carrier gas (600-900°C)

2. Low Temperature (~<600°C) Silox, Pyrox, Vapox and Nitrox^**
   1. Silicon Dioxide (SiO₂) or p-doped SiO₂
      1. Silox

         SiH₄ + 2 O₂ + Dopant —> SiO₂ + 2 H₂O

         N₂ carrier gas (200-500°C)

      2. Pyrox

         SiH₄ + 2 O₂ + Dopant —> SiO₂ + 2 H₂O

         N₂ carrier gas (<600°C)

      3. Vapox

         SiH₄ + 2 O₂ + Dopant —> SiO₂ + 2 H₂O

         N₂ carrier gas (<600°C)

   2. Silicon Nitride (Si₃N₄)
      1. Nitrox

         3 SiH₄ + 4 NH₃ (or N₂O ^*) —> Si₃N₄ + 12 H₂

         N₂ carrier gas (600-700°C)

3. Low Temperature Plasma Enhance (passivation) (<600°C)

   Utilizing radio frequency (RF) or reactive sputtering

   1. Silicon Dioxide (SiO₂)

      SiH₄ + 2 O₂ —> SiO₂ + 2 H₂O

   2. Silicon Nitride

      3 SiH₄ + 4 NH₃ (or N₂O ^*) —> Si₃N₄ + 12 H₂

^* Note: Reactions do not balance stoichiometrically

^** Generic, proprietary or trademark names for CVD reactor systems