WAT, also known as WAT process control monitoring, measures the electrical parameters of a specific test structure after the completion of wafer production and before quality inspection. The purpose is to test the electrical parameters of a specific test structure on a wafer, detect the process condition of each wafer product, evaluate the quality and stability of the semiconductor manufacturing process, and determine whether the wafer product meets the electrical specifications of the process technology platform. WAT data can serve as a quality certificate for wafer product delivery, and in addition, WAT data can reflect the actual production situation of the production line. By collecting and analyzing WAT data, the situation of the production line can be monitored, and the trend of changes in the production line can be judged, providing early warning for possible situations.

The design of integrated circuits is often very complex, including complex circuits. Therefore, chips need to undergo various tests before leaving the factory to ensure that their electrical parameters meet the standards and ultimately ensure that the chips can operate normally in the terminal product. The tests involved include raw material inspection, wafer front end process (FEOL) monitoring, wafer back end process (BEOL) monitoring, wafer acceptance testing (WAT), wafer yield testing (Chip Probing or Circuit Probing, CP), chip packaging process monitoring, chip final test (FT), system level test (SLT), etc. WAT testing includes most of the parameters of the devices used, such as the resistance value of resistors The gate oxide layer capacitance value of MOS, the characteristics of MOSFET, etc.

With the increasing complexity of modern integrated circuit design and the large number of components contained in wafers, it also poses many challenges for testing:

Electrical noise interference:

Electrical noise generated by electromagnetic radiation, induction, or current coupling can cause interference with electrical signals, which can have a negative impact on the accuracy and stability of testing, leading to distortion and unreliable test results.

Electromagnetic interference:

During wafer testing, electromagnetic interference may occur between different test signals. This may lead to distortion of test results or introduce other issues during the testing process.

Temperature management:

Testing on high-density integrated circuits significantly increases power consumption and heat. The increase in temperature will affect the performance and reliability of the circuit. Therefore, ensuring the stability and uniformity of the temperature during the testing process, as well as active and timely heat dissipation, are the key to ensuring the accuracy of the test results.

The TC200 ThermoChuck, developed at a medium to low temperature range, has a wider temperature range of -65 º C to+200 º C, low noise, and a DC control system. Up to 5 temperature and ramp/soak/cycle thermal cycling devices can be set on the front panel, without the need for liquid nitrogen or any other consumable refrigerants. Efficient cooling system for reliable and low-temperature testing of hybrid vehicles and other high-power equipment.

TC200 ThermoChuck features:

The temperature controlled vacuum chuck can accommodate 300mm wafers

High precision, good temperature control, and uniform stability

Can provide standard, high isolation, and protective configurations

The advanced chuck design provides low stray capacitance and high grounding resistance, and the DC power supply can minimize electrical noise

It can interface with manual or automatic detection stations, laser cutters, or inspection stations.