Oxygen Plasma Damage in Boron‐Diffused Silicon

Abstract

Transistor p‐n junctions are observed to have leaky electrical characteristics and increased resistivity after exposure to oxygen plasma. Heating the devices above 180°C for at least 10 min in vacuum, nitrogen, forming gas, or air eliminates the problem and returns the desired electrical characteristics. Experiments indicate that the increase in resistivity is associated with a boron displacement from silicon lattice sites. Additional experiments indicate that this phenomenon can be caused by reactively ion etching or plasma ashing a bare silicon surface which is doped with boron.