X-ray absorption-based technique to measure the thickness of multi-layered structures

The gray level information gathered from using the X-ray absorption-based technique was used to determine the thickness of multi-layered structures in semiconductor components. Various thickness combinations of silicon, copper, tin and silver material were used to construct a range of triple-layered structures. The minimum thickness resolution achievable in copper and tin, for both silicon–copper–tin (Si–Cu–Sn) and silver–tin–copper (Ag–Sn–Cu) combinations were in the order of 0.001 mm. This value was comparable to a single layer of copper and tin, respectively. The gray level information was also applied to detect the presence of a void or an imperfect solder bump, which is increased of approximately 7% and 30–40%, respectively, in the gray values was observed compared to a defect-free and complete solder.