Robust endpoint detection for dielectric etching in low open area devices by laser absorption spectroscopy

As semiconductor device technologies continue to scale down, the manufacturing process becomes increasingly complex, requiring advanced dielectric patterning processes with multiple layers and materials. Plasma etching plays a critical role in achieving precise patterning profiles, with Endpoint Detection (EPD) ensuring accurate over-etch control. Traditional Optical Emission Spectroscopy (OES)-based EPD faces significant challenges with high aspect ratios and low open area designs in next-generation devices. Advanced techniques, including Quantum Cascade Laser Absorption Spectroscopy (QCLAS), offer a robust solution for EPD in dielectric etching with open areas below 1%. Experiments demonstrate that QCLAS significantly outperforms OES in terms of sensitivity, accuracy, and robustness, particularly in detecting etch byproducts in silicon nitride (SiN) capping layers. The study highlights QCLAS’s potential to overcome the limitations of OES in cutting edge device structures, ensuring reliable chip performance in advanced semiconductor manufacturing. This advancement is crucial for maintaining the integrity and functionality of increasingly miniaturized semiconductor devices.