Intelligent Automatic Serial Sectioning using Ultra Short Pulse Laser Polygon Scanning

Serial sectioning of microelectronics, as needed for performing destructive, high-resolution reverse engineering and   failure analysis, faces several challenges, due to the ever-growing miniaturization of features of interest. Some of these challenges are as follows: (1) Current methods of delayering require access to multiple pieces of mechanical equipment such as semi-automated polishing machine, semi-automated milling machine, laser, gel etch, computer numerical control (CNC) milling machine, and ion beam milling machine; (2) A streamlined workflow often does not exist and the quality of the process, to a great extent, depends on operator’s skills; (3) Maintaining the planarity of the layers is a very challenging task using the current technology; (4) Relocating the sample between the delayering and imaging equipment puts the integrity of the sample at risk, gives rise to post-alignment and repeatability issues and significantly increases the time associated with the process; (5) Throughput of the current methods is low, if repeatability and reliability are of concern; (6) Material selectivity comes at a high cost, namely very low material removal rate; (7) Multiple samples may be needed for the reverse engineering process, with one sample for ach layer. However, this may be problematic as the layer thickness may be different within the set of used samples, due to the variations present during the manufacturing process. Our proposed solution, the feasibility of which will be investigated in phase I, is an all-in-one tool that can address the abovementioned challenges. This tool features femto-second pulsed laser, that enables athermal ablation, integrated with a polygon scanning system, that enables rapid, accurate and repeatable material removal, laser induced breakdown spectroscopy (LIBS), that enables real-time elemental analysis and material selective removal, and machine learning (ML) algorithms for controlled, high-precision, high-throughput material ablation. The tool incorporates a co-axial-with-laser far working distance digital microscope for real-time monitoring of the ablation process while performing imaging up to 1000X magnification. Further, a transfer shuttle will be integrated for fast, high-precision, successive transfer of sample among the material ablation component and the high-resolution imaging components (e.g., scanning electron microscope (SEM)) without the need for breaking the environmental conditions of any of these compartments, also enabling correlative multi-modality inspection. In addition, an analysis module, that will leverage state-of-the-art image processing and analysis algorithms will be developed for automated decision making about the serial sectioning procedure. Finally, a user-interface/visualization module will be added for seamless serial sectioning jobs that is flexible and customizable for different types of users.