Electrical properties of contact etched p-Si: A comparison between magnetically enhanced and conventional reactive ion etching

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Abstract
We report the results of a comparative study of the damage induced in boron‐doped Si by contact etching. The two approaches compared are conventional reactive ion etching and magnetically enhanced reactive ion etching (MERIE). The two structure‐chemistry combinations used are SiO2/Si with CHF3/O2 plasmas, and bare Si wafers with CHF3/Ar plasmas. The damage examined in the Si substrates of both structures is that of electronic states in the band gap, the permeation into Si of hydrogen, and the deactivation of boron acceptors. These types of damage are explored by means of deep level transient spectroscopy and capacitance‐voltage measurements on Ti/Si Schottky diodes fabricated on the etched substrate surfaces. The gap states induced by these contact etches are ascribed to interstitial‐atom‐related defects which are proposed to be formed as a result of interactions involving self interstitials. During etching these defects are observed to be both generated by the etching process itself as well as electrically passivated by permeating hydrogen. The hydrogen permeation of the substrate, monitored via acceptor deactivation, is seen to be enhanced for MERIE with increasing magnetic field intensities.