February_EDFA_Digital

edfas.org 5 ELECTRONIC DEV ICE FA I LURE ANALYSIS | VOLUME 24 NO . 1 For the AE crack detection experiments, a one-of-a- kind test bench called Probe Force Investigation Tool (PROFIT) was used (see Fig. 4). This platform, which was developed and assembled in-house at Infineon Technologies AG, enables time-synchronized measuring of both the contact force and AE signals during contacting of test structures with an indenter. The test bench consists of several commercial instru- ments, which are connected by Ethernet interface and controlled by a LabVIEW program. One component is a three-axis motorized stage with a 200 mm wafer vacuum chuck on top. The stage controller unit, which is connected to the stages, provides an accurate positioning in x -, y -, and z -direction. The sensor-indenter system is placed into an AE sensor holder and fixed by screws. The holder is connected to the DMS force sensor, which is assembled with a two-axis tilting stage to compensate a tilting error of the indenter relative to the surface of the test structure. The signal of the force sensor is fed into a force controller unit. The signal of the AE sensor is fed into a preamplifier, which is further connected to an AE controller unit. The voltage signal of the force sensor, which is converted into a cali- brated contact force later, is measured parallel to the AE signals in time synchronization. Therefore, the analog signal of the force sensor is fed into the parametric input of the AE controller unit, where the synchronization takes place automatically. Toexactlyposition the indenter tip to the test structure, a camera alignment system is installed on the frame. The PROFIT is further equipped with a desktop PC including two monitors, a mouse, and a keyboard. The whole test bench is placed on a passive vibration isolation table to compensate external disturbances and shocks, which can generate errors in the sensitive AE measurement. ACOUSTIC EMISSION CRACK DETECTION ON MULTILAYER STACKS MULTILAYER STACK TEST SAMPLES For the acoustic crack experiments various crack- sensitive test structures with alternating metal and oxide Fig. 3 Realized sensor-indenter system. [1] Fig. 4 Test bench PROFIT for AE crack experiments.