New Product: SiC Wafer Inspection/Review System
[WASAVI Series SICA61]

Lasertec has commercialized a SiC Wafer Inspection/Review System [SICA61] that has capability to inspect crystal defects of SiC wafer utilizing bright-field optics and also to observe defects with high resolution.

Along with the growing energy-saving consciousness in the worldwide scale, the importance of new technologies for heightening energy efficiency as high as possible is intensifying, in parallel with pursuit of new energy sources.
Power conversion equipments utilizing power devices have been widely used not only in home appliances but also in industrial instruments and the application field of power conversion equipments is expanding to electric cars, photovoltaics, fuel cells and such, in recent years. However, power loss of silicon (Si) currently used as the material for power devices is large and improvement of power conversion efficiency is sought.
Silicon Carbide (SiC), in comparison with Si, has breakdown electric field about 10 times larger and thermal conductivity 3 times larger. For this reason, SiC is expected to be a successor to Si due to the fact that the power loss of the device based on SiC could be reduced to one severalth.
In recent years, control issue of crystal defects such as micro pipe, which has been a long lasting problem in the SiC crystal growth has begun to look brighter and the development of defect control technology for epitaxial layer of SiC is now widely performed. However, the conventionally used defect inspection tools based on scattering light mode has difficulty in detecting minute crystal defects that scatter only very weak light of very low intensity and also in obtaining stable inspection results due to the factors such as the effect of light reflected at the wafer back surface and the effect of step bunching peculiar to the epitaxial crystal growth. In addition, defect classification for specifying defects that influence the device characteristics is strongly needed.

SICA61 has implemented high detection capability for crystal defects such as shell pit, stacking fault, carrot, micro pipe and such, and also for shallow scratch by solving problems such as step bunching peculiar to epitaxial crystal growth and the effect of light reflected at the wafer back surface, based on the combined technology of confocal optics that is the core technology of Lasertec and differential interferometry, and by the employment of a unique auto-detection algorithm for defects.
Furthermore, SICA61 is equipped with a high resolution review function, a defect classification function, a defect map display function and a 3D measurement function, and is thus adaptable to all the stages from R&D stage through mass production stage.

• Combination of confocal optics and differential interferometry best suited for SiC wafer
• Detect crystal defects such as shell pit, stacking fault, carrot and such with high sensitivity
• Stable defect inspection free from effect of reflected light at the back-surface
• Review function of high resolution
• Defect map display function, defect classification function and high resolution 3D shape measurement function

• Evaluation and analysis of SiC epitaxial crystal growth processes
• Process management of SiC wafer manufacturing
• Outgoing and incoming inspection of SiC wafers