Arsenic Drift in SiO2: Temperature, Dose, and Thermal Gradient Effects

Abstract

Thermomigration of arsenic in in a temperature gradient was recently reported. This technique for dopant movement from into Si creates an efficient oxide diffusion source and is the only known method of forming buried n+ conductive layers in single crystalline Si films thicker than 5 μm formed on oxidized single crystalline Si substrates. Such structures are useful for high‐voltage and/or high‐power devices. Our knowledge of the arsenic drift behavior is extended here and shows an Arrhenius dependence of drift velocity on temperature in the range 1250°–1405°C, no dependence on the ion‐implanted dose in the range , and a linear dependence on the thermal gradient. The loss of arsenic from the migrating zone by Fickian diffusion is a function of the ion‐implanted dose. Measured losses for 1000Å of movement range from and higher doses.