Thickness and composition measurement for thin film with combined X-ray technique

Newly introduced thin film materials such as Pb(Zr,Ti)O/sub 3/ (PZT) present difficulties in the high-precision measurement of thickness and composition, which is essential for process control of film production. X-ray Fluorescence (XRF) is widely used for simultaneous measurement of both film thickness and composition. However, problems arise when XRF is applied to PZT/Pt/Ti stacked films, which comprise the most common structure for ferroelectric RAM (FeRAM) capacitors. The X-ray interference method (XI) based on X-ray reflectivity measurement (XRR) is known to enable absolute thickness measurement of film. On the other hand, grazing incidence X-ray fluorescence (GIXRF) is a surface-sensitive method that is suitable for composition measurement of PZT deposited on Pt/Ti layers. The authors have developed a combined X-ray apparatus that has the functions of XI and GIXRF and can be used to control the production of multilayer film for FeRAM capacitors.