Effect of Halogen salts and Surfactants in Slurry on InGaAs and InP CMP

Abstract

Attempts are being made to use a III-V material having electron mobility faster than Silicon as a channel material due to the demand for a high-performance CMOS (Complementary Metal-Oxide Semiconductor) device. In order to implement these III-V materials in CMOS channels, chemical mechanical polishing (CMP) step is essential. However, there are few CMP process studies for III-V materials. In this study, the removal rate, roughness, and particle contamination of III-V wafers were compared according to the pH of the slurry. Then, the change of III-V material according to pH was analyzed using the surface analysis of the wafer. Through previous experiments, it was confirmed that the addition of halogen ion to the alkali slurry can improve the removal rate, roughness, and particle contamination. Wafer surface analysis was performed to find the mechanism. The wafer thickness was measured using spectroscopic ellipsometry and the roughness of the substrate was measured using atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis was performed for elemental analysis of the substrate surface. After CMP, sodium dodecyl sulfate (SDS) was added to the slurry to reduce contaminant particles on the substrate. Contamination particles and roughness were measured using AFM, and the removal rate by surfactant concentration was measured using spectroscopic ellipsometry. To measure surfactant remaining on the substrate, residual organic was analyzed using fourier-transform infrared spectroscopy (FT-IR).