Silicon Carbide (SiC)

For several decades silicon (Si) has been the preferred material for nearly all semiconductors. Processing of silicon has become very mature and cost efficient.

Research on alternative materials is about as old as the application of silicon. In particular so called wide bandgap semiconductors (like gallium nitride GaN and silicon carbide SiC) have very interesting characteristics. For high performance power semiconductors SiC is the preferred choice.

 

 

These characteristics result in significantly of SiC power devices compared to silicon based components.

higher current density	→ compact solutions
higher operating temperatures	→ increased ruggedness
higher breakdown field	→ high voltage FETs/SBDs
reduced static and dynamic losses	→ higher efficiency

The wide bandgap causes a threshold voltage of about 3 V for bipolar components. For applications < 2000V to 3000 V unipolar devices (Schottky Diodes, FETs) are therefore better suited than bipolar devices.

Development of SiC wafers, the raw material for SiC power semiconductors, has been very successful over the past years in achieving major improvements in quality, yield and diameter. However, there are in particular three areas where SiC wafers are still significantly behind state of the art silicon wafers:

• SiC wafers are available with diameters of 3", moving to100mm
  
• Manufacturing compatibility to Si wafers (currently up to 8") is limited; higher cost
  
• SiC wafers still have larger defect numbers / cm² than Silicon
  
• Acceptable yield yet for smaller chips only, higher cost than Si
  
• Manufacturing processes for SiC crystals are technologically demanding
  
• SiC components will remain more expensive than Si components