Silicon manufacturing involves multiple processes to make sure that the wafer produced is one of superior quality. A crucial part of this manufacturing process is the inspection stage. If you’re wondering how a thin delicate material called a wafer is inspected, here’s how:
Using a wafer defect inspection system, foreign objects called particles are detected and classified into two types of defects: random defects and systematic defects. Random defects refer to particles that adhere to the wafer’s surface. On the other hand, systematic defects refer to the defects produced from the state of the mask and exposure method. They appear in locations where the exposure state is very difficult and require fine alteration. Inspection is divided into two inspection systems, a patterned wafer inspection system and a non-patterned wafer inspection system.
The patterned wafer inspection system is able to identify defects by examining the pattern images of neighboring chips or dies and gathering the difference. Here are some of the many types of patterned wafer inspection systems:
Electron Beam Inspection System: On the surface of a wafer, the electron beam is illuminated to detect the number of defects as a voltage contrast according to the dynamism of the instrument’s internal wiring.
Bright-Field Inspection System: Commonly used for detailed inspection of pattern errors.
Dark-Field Inspection System: This system is designed for large numbers of wafer defect inspection at high speed.
This type of inspection is commonly conducted by wafer manufacturers before a wafer is shipped. A dummy bare wafer is used to monitor the cleanliness and condition of the machinery. A laser beam will be launched towards a rotating wafer to detect defects using scattered light. The positioning of the particles or defect will then be calculated and recorded.
Wafer inspection is a crucial step in silicon manufacturing. If you want quality wafers for your business, get it from Wafer World! Call us today for any inquiry or purchase wafers online!