Surface damage in Si substrates created by Arhyphen;ion milling or by reactivehyphen;ion etching in CF4, CHF3, Cl2, SiCl4, or SiF4has been investigated. Metalhyphen;oxidehyphen;semiconductor capacitors were fabricated on the etched Si substrates, and the interfacehyphen;state densities were obtained from capacitancehyphen;voltage measurements. Interface states generated by the dry etching processes were strongly dependent on the etching gas and the bias voltage. Carbonhyphen;based gases (CF4, CHF3) induced more interface states than those without carbon. For the carbonhyphen;based gases, Si samples etched in CHF3showed lower densities of interface states than samples etched in CF4under the same conditions. Generation lifetime measurements indicated that samples with large densities of interface states also had short lifetimes. Measurements of oxidationhyphen;induced stacking faults caused by dry etching were consistent with both the interfacehyphen;state and lifetime measurements. Thermal annealing of the etched wafers was not effective in reducing the surface damage. The measured interface states on the dry etched Si substrates could be lowered to their prehyphen;etched levels by removing at least 500 Aring; of the etched surface by wet chemical etching.
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