A Nanofluidic Sensor for Real-Time Detection of Ultratrace Contaminant Particles in IC Fabrication

When the feature size of integrated circuits (ICs) reaches nanometer, nano contaminant particles (CPs) on the surface of semi-finished devices during processing may cause serious device defects, while effective real-time CP detection techniques are still unavailable, especially when the CPs are of low concentration. Using a gold interdigitated electrode fabricated on a ceramics substrate, a sensitive sensor for ultra-trace nano CP detection in cleaning fluids is developed, which employs an optimized detection signal integrating the nanofluidic enrichment of nanoparticles (NPs) into interfacial capacitance measurement. The detection can achieve a limit of detection of 10 ² particles/mL with a response time of 30 s. The logarithmic linear range of this sensor reaches (10 ² - 10 ⁷ ) particles/mL for CPs of 10 nm in grain diameter, which can meet the test demand of practical concentration. This sensor has capability to detect CPs of different material and size, and the operation is real-time and nondestructive. In addition, it is demonstrated to work reliably in solutions with different conductivity. The detection protocol is simple, and the sensor as well as the impedance analyzer for test also has advantages in portability and cost efficiency for industrial-scale on line application. This work provides a feasible and promising approach for IC fabrication's quality evaluation through ultra-trace nano CP detection in used cleaning liquid samples.