P‐82: Non‐Destructive Measurement of Metal Thickness in Displays Using Energy Dispersive X‐Ray Spectroscopy (EDS)

Previously various optical, electrical, scanning, and destructive methods have been used to measure layer thickness. However, when measuring metal thickness, such methods either lack optical transmission, cause surface damage, or require sample destruction. Such drawbacks brings limitation in measurable sample type, loss of measured sample, and loss in overall production yield. Therefore, a non‐destructive method for measuring metal thickness is essential for minimizing sample loss and maintaining production yield. In this study, an energy dispersive X‐ray spectroscopy (EDS) was proposed as a non‐destructive and sensitive method for measuring metal thickness. Based on the results of EDS, the metal thickness was calculated using intensity analysis method or ratiometric analysis method. The feasibility was first confirmed through Monte Carlo simulation for various metal types and thicknesses. The proposed method was further tested with copper and silver metal layer sputtered on glass substrate. Both the intensity and ratiometric analysis method positive linear relation as a function of metal thickness. However, the intensity analysis method showed slight difference in absolute intensity value between the measured modules, possibly due to the relative difference in sensitivity. The ratiometric analysis method, which calculates the ratio of the target to a secondary material, could compensates the sensitivity variation and showed equal and applicable results regardless of the detection modules. The results were further compared to conventional sheet resistance, and showed high sensitivity for all thickness. In conclusion, the proposed method is a sensitive and reliable measurement method of metal thickness and may a solution for non‐destructive measurement in various fields of semiconductor, display, and battery.