Evolution of hydrogen induced defects during annealing of plasma treated Czochralski silicon

Abstract

Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used to study the temperature evolution of hydrogen plasma induced defects in silicon. Hydrogen plasma treated n- and p-doped Czochralski silicon samples were annealed at temperatures between 200 and 1000°C for up to 10h in air. Platelets are formed on {111} and {100} crystallographic planes. The structural defects are similar in n-type and p-type material. Small defects at the surface anneal out at temperatures above 400°C and {111} platelets start to dissolve above 500°C, except in highly p-doped samples where the platelets are stable up to 600°C. The hydrogen penetrates deeper into a low doped than a high doped sample, resulting in platelet formation deeper into the sample. At annealing temperatures above 800°C, an amorphous oxide layer forms at the surface of the sample. New platelets form after 1h annealing at 1000°C. The roughest surface is found in highly n-doped samples, hydrogenated at high plasma frequency for long exposure times. For high annealing temperatures the roughness decreases.