Experimental Determination of Si Self-Interstitial Emission During Oxide Precipitation in Czochralski Silicon

Abstract

We used the method of Torigoe and Ono [J. Appl. Phys., 121, 215103 (2017)] to investigate the kinetics of β, the number of self-interstitials emitted per precipitated oxygen atom, during oxide precipitation in Czochralski silicon. For this purpose, we used pp- epitaxial wafers with a buried highly B-doped epitaxial layer which were annealed with and without thermal pre-treatments at 950 °C. From the results we conclude that in the initial phase of oxide precipitation without thermal pre-treatment β is very high before it drops to low values. With a thermal pre-treatment at 800 °C for 2 h, the initial value of β is somewhat lower before the drop also occurs. If a nucleation anneal is carried out before the thermal treatment at 950 °C the β values are low from the beginning. All of these results confirm our previously published theoretical predictions experimentally. This work also shows that the crystal pulling process can affect the initial β value because grown-in oxide precipitate nuclei can reduce their strain by vacancy absorption. Therefore, high vacancy supersaturation during crystal cooling while oxide precipitate nucleate would lead to somewhat lower initial β values.