The direct measurement of the memory state (i.e. bit at “0” or at “1”) on single magnetic tunnel junction (MTJ) in a commercial magnetic random access memory (MRAM) remains challenging. In this paper, we propose a probing approach to investigate the MTJ resistance and by this way determine the memory state. To reach this goal, the MRAM device needs to be prepared to create an electrical access to both sides of the MTJs. The suitable methodology consists in a backside preparation routine that creates a bevel allowing us to access the bottom side of the MTJs through vias and the top side to the bitlines. After that, two approaches are discussed to establish the electrical connection. First described is the nanoprobing technique where the electrical connection is created by two nanometric tips positioned in contact on vias and bitlines thanks to a scanning electron microscope. It is then possible to collect the current flowing through the MTJs and to evaluate the resistance. A resistance around 12 kΩ and 14 kΩ were determined for “0” and “1” bits respectively, which is in agreement with literature. Secondly, these measurements will be compared to those resulting from a near-field probing experiment done in a conductive mode. A resistance around 19 kΩ and 24 kΩ were determined for “0” and “1” bits respectively. The use of both methods allows for a cross-reference between the resistance values and a discussion on the advantages and drawbacks of both probing techniques.

Recent planar technologies with 3 metal layers or more challenge current physical design modification capacities using Focused Ion Beam tools. Image visibility on the FIB is drastically reduced, making accurate positioning and milling operations in the area of interest more difficult, and the use of power planes increases the risk of short circuits while accessing inferior metal lines. Despite the complexity of FIB modifications, however, the demand for circuit modifications continues to increase. To respond to this demand for successful, time efficient, FIB modifications, step by step monitoring of operations is imperative. In this paper, we will present an innovative method which brings in-situ electrical monitoring and contactless measurement capabilities to FIB systems. Electrical connection of the circuit inside the vacuum FIB chamber is done using a commercial load module and logic waveform acquisition with the FIB is obtained without modifying FIB hardware using a voltage contrast approach. With this method, it is possible to verify the completion of FIB milling and depositing operations by temporarily suspending FIB action so that a test pattern can be run allowing electrical testing and measurements of the circuit without damaging it.