HF-9012 Photovoltaic Silicon Wafer Bending Testing Machine
The bending of a silicon wafer refers to the amount of convex or concave deformation at the center point of the median surface of the wafer. The main measurement methods include contact and non-contact types. Bending is one of the key quality indicators of silicon wafers. Variations in wafer thickness tolerance, total thickness (parallelism), and surface finish are mainly caused by changes in bending. Although the precision of the slicing machine itself can affect these parameters, it will not result in thickness or total thickness fluctuations reaching tens or even hundreds of microns.
1.1 Contact Measurement Method
Place the silicon wafer on three support points of a reference ring, which together form a reference plane. Use a low-pressure displacement indicator to measure the distance the wafer center deviates from the reference plane. Flip the wafer and repeat the measurement. Half of the difference between the two measurements represents the wafer’s bending value.
2.1 Non-Contact Measurement Method
Place the silicon wafer with its front side facing up on three support points of a reference ring, which form a reference plane. Use a non-contact probe to measure the distance the center point of the wafer deviates from the reference plane. Flip the wafer and repeat the measurement. Half of the difference between the two measurements represents the wafer’s bending value.
