# Numerical Simulation-Based Study of Controlled Particle Deposition Technology for Wafer Surfaces
###### Abstract  
Scanning surface inspection systems (SSISs) require standard wafers (SWs) with traceable particle characteristics for accurate calibration. Achieving controlled particle deposition on wafer surfaces is essential for the fabrication of such SWs. In this study, numerical simulations were conducted using Fluent to systematically investigate the effects of key deposition parameters--including nozzle diameter, nozzle-to-wafer distance, chamber volume, rotation speed, and particle size--on deposition efficiency and uniformity. Based on the simulation results, a generation-deposition system was developed, incorporating a differential mobility classifier (DMC) to produce monodisperse aerosols. The particles used in the experiments were polystyrene latex (PSL) particles with diameters of 70 nm, 100 nm, 140 nm, and 200 nm; the wafers used were 50 mm silicon wafers. Experimental validation was carried out using scanning electron microscopy (SEM) and SSISs. The optimal deposition conditions were identified as a nozzle diameter of 4 mm, nozzle-to-wafer distance of 15 mm, chamber volume greater than 657 cm\({}^{3}\), and a rotation speed of 0.314 rad/s. Under these unified parameters, particles with diameters \(\geq\)100 nm could be effectively deposited, while smaller particles required additional adjustments. The developed system enables the preparation of SW with traceable particle sizes and uniform deposition, fulfilling the fundamental requirements for SSIS calibration. m o n o  
2. The system's inability to provide direct defect imaging necessitates establishing a reference correlation between standard particle sizes and scattering intensities, requiring subsequent conversion of measured signals into equivalent standard dimensions [8]. Therefore, SSIS calibration using standard wafers (SWs) becomes essential to guarantee detection accuracy and consistency. SWs are a type of standard material primarily characterized by controlled particulate contamination [9; 10]. The composition, particle size, and deposition patterns on these wafers are precisely regulated. Researchers achieve controlled particle deposition on the wafer surface through the electric mobility technology screening of particle size [11; 12], combined with electrostatic force [13; 14; 15], inertial force [16; 17; 18], thermophoretic force [19; 20] and other multi-physical field effects for deposition behavior regulation. However, the existing technology still has significant limitations. The electrical deposition system is highly efficient, but the electric field parameters need to be adjusted dynamically according to the characteristics of the particles, which quickly leads to non-uniform deposition. The non-electrical deposition system can avoid charge interference. However, it is challenging to meet the demand for high-precision calibration due to the high complexity of the equipment and the residual contamination of liquid droplets. In addition, the simulation of aerosol dynamics inside the deposition chamber is still insufficient, and the quantitative analysis of turbulence effects and particle-flow coupling is lacking. To address the above challenges, this study utilizes computational fluid dynamics (CFD) to simulate and optimize the flow field parameters within the deposition chamber. The influence of particle size, chamber geometry, and the coupling of external force fields on particle deposition behavior on the wafer surface is systematically analyzed. Based on the simulation outcomes, an integrated generation-deposition system was developed for the preparation of standard wafers (SWs). Polystyrene latex (PSL) particles with diameters of 70 nm, 100 nm, 140 nm, and 200 nm were used to generate monodisperse aerosols via an aerosol generator and a particle size classifier, and these were subsequently deposited onto silicon wafers using the optimized deposition chamber. This work provides theoretical guidance for the engineering-scale fabrication of SWs and proposes a novel calibration solution for scanning surface inspection systems (SSISs).