Measurements of dynamic characteristics of intermediate layer in thin semiconductors

A vibration test method for investigating the dynamic characteristics of thin multi-layered semiconductor wafers was proposed. Flash memory chips whose thickness was varied by grinding the wafers were used as specimens. The specimens composed of silicon, device, and device-protecting layers were excited at the clamped end by using a shaker attached to the clamping device. The vibration of the beam was measured using a laser vibrometer. The wave approach was used to analyze the vibration, from which the complex bending stiffness was determined. A theoretical model to obtain the dynamic characteristics (Young's modulus and the loss factor) of the intermediate device layer by using the measured bending stiffness was investigated. The results were examined and compared with those of a nanoindentation test to verify the accuracy of the model. The proposed method enabled determination of the dynamic properties of the intermediate layer without separation which are essential for understanding the impact response of the wafers during manufacturing process.