Current imaging, EBIC/EBAC, and electrical probing combined for fast and reliable in situ electrical fault isolation
Abstract Using a compact nanoprobing setup comprising eight probe tips attached to piezo-driven micromanipulators, various techniques for fault isolation are performed on 28 nm samples inside an SEM. The employed techniques include nanoprobing as well as EBAC. The recently implemented Current Imaging technique is used to quickly image large arrays of contacts providing a means of locating faults. In this case, Current Imaging provides insight into the sample's behaviour yielding qualitatively comparable results to the more cumbersome cAFM technique. While the results of the TEM investigations including EDX mappings were inconclusive, the Current Imaging technique clearly shows that the root cause is located below the SiGe layer. By combining these techniques inside a FIB/SEM microscope, it is possible to locate and characterize a failure as well as prepare a TEM lamella for further investigation without the necessity to switch to a different tool.
Method of Precise Positioning for Defect Failure Analysis Based on Nano-Probing and EBAC
Failure analysis (FA) becomes increasingly crucial for semiconductor industries with the scale-down and larger integration of devices. In order to overcome the limitation of traditional optical resolution for FA techniques, this article proposed an effective method of precise positioning of circuit defect based on localized probing technique, nano-probing and electron beam absorbed current (EBAC). Open circuit, short circuit and gate/capacitor oxide defects were the most common failures in IC manufactures, therefore representative examples based on these failures were employed to illustrate the analysis procedure and effectiveness of the proposed method. Scanning electron microscope (SEM), focused ion beam (FIB) and transmission electron microscope (TEM) results were presented to verify the accuracy of the positioning. It was demonstrated that the proposed precise positioning method was able to accurately locate the defect position, and was useful for determining the failure mechanism as well. The method showed great potential for improving the success rate of FA for semiconductor devices.
Two dimensional plotting of semiconductor resistivity by scanning electron microscope
Abstract A method for the measurement of the resistivity of semiconductor samples is described which uses the electron beam of a scanning electron microscope as probe. This technique provides high local resolution (about 10 μm), causes no damage of the semiconductor material and is fast so that the two dimensional distribution of the resistivity can be plotted on a cathode ray tube. The sample, however, must be prepared to have a large area blocking Schottky-contact. The focussed electron beam generates carriers in a space charge region below a thin metal contact. The measurement is based on the change of the I-V characteristic of the Schottky diode caused by the spreading resistance from the point of the carrier generation to the bulk. Experimental results are presented as well as a theoretical evaluation of the sensitivity of this measuring technique.