MEASUREMENT OF DEFECT PROFILES IN REACTIVE ION ETCHED SILICON

Reactive ion etching (RIE) is used as a method of pattern transfer and anisotropic etching for contact windows to shallow junctions in IC manufacture. We use photoluminescence (PL), junction current-voltage (I-V), transmission electron microscopy (TEM), and Rutherford backscattering (RBS) to characterize the defects introduced in silicon by the RIE process. A displacement damage region extends approximately 1000 angstrom with defect concentrations greater-than-or-equal-to 10(18) cm-3, depending on the etching parameters. A defect reaction region continues from the displacement damage to depths greater than 1-mu-m. The extent of the defect diffusion is limited by trapping of interstitial silicon at impurity sites. We use anodic oxidation followed by HF acid etch to remove material in 250 angstrom steps, and then employ the combination of optical (PL), physical (RBS, TEM), and electrical (I-V) measurements to provide a complete defect profile of the near-surface region.