Exposure Characteristics of Nanoparticles as Process By-products for the Semiconductor Manufacturing Industry

Abstract

This study aims to elucidate the exposure properties of nanoparticles (NPs; <100 nm in diameter) in semiconductor manufacturing processes. The measurements of airborne NPs were mainly performed around process equipment during fabrication processes and during maintenance. The number concentrations of NPs were measured using a water-based condensation particle counter having a size range of 10–3,000 nm. The chemical composition, size, and shape of NPs were determined by scanning electron microscopy and transmission electron microscopy techniques equipped with energy dispersive spectroscopy.

The resulting concentrations of NPs ranged from 0.00–11.47 particles/cm³. The concentration of NPs measured during maintenance showed a tendency to increase, albeit incrementally, compared to that measured during normal conditions (under typical process conditions without maintenance). However, the increment was small. When comparing the mean number concentration and standard deviation (n ± σ) of NPs, the chemical mechanical polishing (CMP) process was the highest (3.45 ± 3.65 particles/cm³), and the dry etch (ETCH) process was the lowest (0.11 ± 0.22 particles/cm³). The major NPs observed were silica (SiO₂) and titania (TiO₂) particles, which were mainly spherical agglomerates ranging in size from 25–280 nm. Sampling of semiconductor processes in CMP, chemical vapor deposition, and ETCH reveled NPs were <100 nm in those areas. On the other hand, particle size exceeded 100 nm in diffusion, metallization, ion implantation, and wet cleaning/etching process. The results show that the SiO₂ and TiO₂ are the major NPs present in semiconductor cleanroom environments.

Keywords:

• by-products
• exposure characteristics
• nanoparticles
• semiconductor