Anodic Dissolution of N+ Silicon

An experimental study has been made of the anodic dissolution of silicon in aqueous HF solution with emphasis on heavily doped n‐type. Current‐voltage curves, the effective dissolution valence, and the critical current density have been determined for n, n + , and p samples. Since n + silicon has a resistivity less than 0.05 ohm‐cm, it can be electropolished while higher resistivity material exhibits a current saturation effect although breakdown occurs at only a few volts. Minority carrier generation within the space charge region does not account for the magnitude of the saturation current for n‐type and extensive attack was evident at the surface of n‐type which had received prolonged anodic treatment. The critical current density for n + samples was found to be a function of the resistivity.