Enhanced Passive Voltage Contrast Imaging Using a Compound Lens Enabled by In-Lens Detector Optimization for Advanced Semiconductor Devices
Enhanced Passive Voltage Contrast Imaging Using a Compound Lens Enabled by In-Lens Detector Optimization for Advanced Semiconductor Devices
Thursday, October 8, 2026: 11:00 AM
Summary:
Passive voltage contrast (PVC) imaging using scanning electron microscopy (SEM) is a key technique for semiconductor failure analysis; however, obtaining clear images becomes increasingly challenging as device dimensions shrink to the nanometer scale, particularly under low accelerating voltage conditions below 1 kV. To address this limitation, this study proposes a PVC imaging approach using a compound lens SEM configuration without specimen bias. The compound lens system, which combines magnetic and electrostatic fields within the same region, enables stable observation with minimal influence from specimen topography or field-of-view shifts. To achieve high-resolution and high-contrast PVC imaging under these conditions, the in-lens detector (ILD) was optimized. Experiments were conducted using a JSM-IT810SHL SEM at an ultra-low accelerating voltage of 0.2 kV, a 1 mm working distance, and a picoampere-level probe current, targeting a 3 nm SRAM device. The optimized ILD significantly enhanced signal intensity compared to the original configuration, enabling clear PVC images under identical conditions. Simulations indicated that detection efficiency for low-energy secondary electrons (4–8 eV) improved to approximately 80%, resulting in improved image visibility, stable automatic adjustments, and faster, more reliable failure analysis.
Passive voltage contrast (PVC) imaging using scanning electron microscopy (SEM) is a key technique for semiconductor failure analysis; however, obtaining clear images becomes increasingly challenging as device dimensions shrink to the nanometer scale, particularly under low accelerating voltage conditions below 1 kV. To address this limitation, this study proposes a PVC imaging approach using a compound lens SEM configuration without specimen bias. The compound lens system, which combines magnetic and electrostatic fields within the same region, enables stable observation with minimal influence from specimen topography or field-of-view shifts. To achieve high-resolution and high-contrast PVC imaging under these conditions, the in-lens detector (ILD) was optimized. Experiments were conducted using a JSM-IT810SHL SEM at an ultra-low accelerating voltage of 0.2 kV, a 1 mm working distance, and a picoampere-level probe current, targeting a 3 nm SRAM device. The optimized ILD significantly enhanced signal intensity compared to the original configuration, enabling clear PVC images under identical conditions. Simulations indicated that detection efficiency for low-energy secondary electrons (4–8 eV) improved to approximately 80%, resulting in improved image visibility, stable automatic adjustments, and faster, more reliable failure analysis.