Semiconductor manufacturing is a complex, multi-step process, and defects or weaknesses that may result in the failure of an IC may be introduced at any process step. Failures may occur immediately or at any time during the operating life of an IC, sometimes after several months of normal use. Semiconductor manufacturers rely on testing and reliability screening to identify and eliminate defects that occur during the manufacturing process.
Testing and reliability screening involve multiple steps. The first set of tests is typically performed by IC manufacturers before the processed semiconductor wafer is cut into individual die, in order to avoid the cost of packaging defective die into their packages. This “wafer probe” testing can be performed on one or many die at a time, including testing the entire wafer at once. Most leading-edge microprocessors, microcontrollers, digital signal processors, memory ICs, sensors and optical devices (such as vertical-cavity surface-emitting lasers, or VCSELs) then undergo an extensive reliability screening and stress testing procedure known as burn-in or cycling, depending on the application. This can either be done at the wafer level, before the die are packaged, or at the package level, after the die are packaged. The burn-in process screens for early failures by operating the IC at elevated voltages and temperatures, at up to 150 degrees Celsius (302 degrees Fahrenheit) or higher. Depending upon the application, the burn-in times can range anywhere from minutes and hours to days. A typical burn-in system can process thousands of ICs simultaneously. After burn-in, the ICs undergo a final test process using automatic test equipment, or testers. For example, this cycling process screens flash memory devices for failure to meet write/erase cycling endurance requirements.
The Company manufactures and markets full wafer contact test systems, test during burn-in systems, test fixtures and related accessories.