1. Process of CP testing
The wafer is placed on the Chuck stage and moved to the position where the camera captures images. Based on the captured images, the center position of the wafer and the direction of grain arrangement are calculated. Then, the Chuck stage is rotated to align the grain arrangement direction with the X-axis;
During testing, move the Chuck table to ensure accurate contact between the probe and the grain solder pad. The upper computer sends a start test signal to the testing machine, which then begins testing and returns the results to the upper computer. Based on the test results, the upper computer decides whether to retest or mark the grain, completing the testing of one grain;
Then the upper computer controls the Chuck table to move to the next grain position to continue testing;
After measuring one row of grains, move to the Y-axis and switch to another row until all grains are measured.

2. Wafer center inspection
In order to obtain the center of the wafer, wafer boundary detection can be performed continuously at three different positions, obtaining three boundary points A, B, and C. Then make the perpendicular lines of AB and BC respectively, and according to the three-point circle determination principle, the center position of the wafer can be calculated. The extraction of wafer boundaries can be divided into three parts: image binarization, image erosion, and edge extraction.
3. Wafer leveling
The wafer is placed on the Chuck stage, and there is an inclination angle between the grain arrangement direction and the X-axis movement direction. The wafer needs to be aligned so that the grain arrangement direction is in the same direction as the X-axis. This way, during the feed motion, only the X-axis or Y-axis movement is required, simplifying the motion control of probe testing.
To calculate the tilt angle of the grain direction, it is necessary to determine the positions of two grains in the same row, calculate the X-direction displacement d and Y-direction displacement Δ y of the two grains, and then use the formula tan θ=Δ y/d to calculate the tilt angle. Then rotating the R axis can achieve wafer leveling.

The temperature chuck TC series developed by Zonglen is an air-cooled high and low temperature chuck system with a temperature range of -65 ℃ to 200 ℃, mainly composed of air-cooled high and low temperature chucks and air-cooled temperature controllers. The system has a wide temperature control range, compact cooling kit, pure air refrigeration, high temperature accuracy and stability control, and is widely used for key parameter analysis of temperature dependent electrical performance of semiconductor devices or wafers with a size of eight inches or less, such as power device modeling and testing, wafer reliability evaluation, production type temperature dependent testing, temperature dependent optoelectronic testing, RF temperature dependent testing, etc.
Key features:
·Only use air cooling without liquid or Peltier components
·The temperature range is -65 ℃ to 200 ℃
·Modular system, suitable for individual testing needs
·Coolant occupies a small area, saving space
·Compatible with major mainstream production or analytical probe stations
·Can integrate a complete set of software and hardware into one