Challenges and Solutions of 2-D (3-D) Device Doping Process and Doping Profiling Metrology

The appearance of 3-D devices and structures, including FinFET, DRAM access device pillar, 4f2 DRAM vertical transistor, and 3D VNAND cell pillar, has changed the doping technologies and doping profiling metrologies. This change also implies that novel concepts for 3-D dopant and carrier profiling measurements are necessary. 1.5-D SIMS can be used to study dopant incorporation in 3-D structures. Scanning spreading resistance microscopy (SSRM) and electron holography (EH) methods have been developed and well-established on 2-D cross-sectional doping profiling measurements. Although SSRM and electron holography approaches are inherently 2-D, extensions towards 3-D structures are capable either by the dedicated design of test structures or by the approaches of mechanical slicing and polishing. Good correlations between 2-D (3-D) doping profiling measurements and device performance have been demonstrated. Thanks to the new 2-D (3-D) doping profiling measurements, plasma doping (PLAD) process has been demonstrated beneficial on 3-D device manufacturing.