Polycrystalline Silicon Carbide

Silicon carbide's strength, thermal conductivity, and stability in extreme environments make it a useful material for electronics and MEMS.

  • Typical Film Thickness: 0.3 µm
  • Batch Size: 25
  • Deposition Rate: 6 - 9 nm/min. (60 - 90 Å/min.)
  • Deposition Gases: Methylsilane, Dichlorosilane, Hydrogen, Acetylene, Ammonia
  • Deposition Temperature: 700 - 900 °C
  • Residual Stress: 200 - 1400 MPa

Some common precursors include:

  • SiH4 + C2H4
  • SiH2Cl2 + C2H2
  • 1,3-Disilabutane
  • Methylsilane

NH3 is commonly used for n-type doping while (CH3)3Al is used for p-type. The recipes using organosilicon precursors can be done at lower temperatures. 1,3-disilabutane, however, has several disadvantages: it is expensive, liquid, and relatively low-purity. Its purity also degrades over time, leading to excessive run to run variation. The methylsilane process is thus recommended. Some process relationships are:

  • Increasing pressure in the range 0.17 - 1.7 Torr increases film stress and decreases growth rate.
  • Around 800 °C, film stress reaches a minimum and the growth rate reaches a maximum.
  • Stress reaches a minimum with the replacement of 9% of the methylsilane with dichlorosilane.

Applications: high-temperature and chemically-resistant MEMS, high-power and high-voltage devices, resonators, passivation.

LPCVD Processes