Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (28권1호 55-63)

Scanning Tunneling Microscopy (STM)/Atomic Force Microscopy(AFM) Studies of Silicon Surfaces Treated in Alkaline Solutions of Interest to Semiconductor Processing

Scanning Tunneling Microscopy (STM)/Atomic Force Microscopy(AFM) Studies of Silicon Surfaces Treated in Alkaline Solutions of Interest to Semiconductor Processing

;
Park, Jin-Goo;

Hanyang University, Department of Metallurgy and Materials Engineering;
Hanyang University, Department of Metallurgy and Materials Engineering;

Abstract

Alkaline solutions such as $NH_4$OH, choline and TMAH (($CH_3$)$_4$NOH) have been introduced in semiconductor wet processing of silicon wafers to control ionic and particulate impurities following etching in acidic solutions. These chemicals usually mixed with hydrogen peroxide and/or surfactants to control the etch rate of silicon. The highest etch rate was observed in $NH_4$OH solutions at a pH in alkaline solutions. It indicates that the etch rate depends on the content of $OH^{-}$ as well as cations of alkaline solutions. STM/AFM techniques were used to characterize the effect of alkaline solutions on silicon surface roughness. In SC1 (mixture of $NH_4$OH : $H_2$$O_2$ : $H_2$O) solutions, the reduction of the ammonium hydroxide proportion from 1 to 0.1 decreased the surface roughness ($R_{rms}$) from 6.4 to $0.8AA$. The addition of $H_2$$O_2$ and surfactants to choline and TMAH reduced the values of $R_{p-v}$ and $R_{rms}$ significantly. $H_2$$_O2$ and surfactants added in alkaline solutions passivate bare silicon surfaces by the oxidation and adsorption, respectively. The passivation of surfaces in alkaline solutions resulted in lower etch rate of silicon thereby provided smoother surfaces.s.ces.s.

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