The effect of oxidation on the diffusion of phosphorus in silicon

Abstract

The diffusion of phosphorus from a thick epitaxial layer into a silicon substrate has been investigated using the spreading-resistance technique. By comparing the diffusion profile under a free oxidized surface with the profile under a masked surface, it has been shown that surface oxidation enhances diffusion at low temperatures and retards diffusion at high temperatures. The conditions which favor enhanced diffusion are those under which stacking faults grow; retarded diffusion is associated with stacking-fault shrinkage. Enhanced diffusion is due to the oxide injecting excess interstitials into the substrate; retarded diffusion is caused by vacancy injection. It is concluded that phosphorus diffuses by the interstitialcy mechanism and that the criterion for interstitial or vacancy injection is the relative value of the anion and cation fluxes across the oxide-silicon interface.

Oxidation Enhanced Diffusion of Phosphorus over a Wide Range of Oxidation Rates

“…Table I shows the final oxidation conditions together with the final oxide thicknesses. This was probably due to the lower oxidation temperature than that for the ORD previously reported (17,18). The staining was carried out with a HF/HNO3 mixture under strong illumination, which effectively distinguished the n-type region from p-type one.…”

“…Impurities, such as phorphorus and boron, diffuse mainly via self-interstitials, wl!ercas antimony diffuses mainly via vacancies. Second, the mechanism of ORD for phosphorus under high-temperature and long-time oxidation (17,18) is still not clear. In the following, two phenomena unexplained by reported models are detailed.…”

Observation of Oxidation-Enhanced and -Retarded Diffusion of Antimony in Silicon: The Behavior of (111) Wafers

“…The V injection is characterized by a constant rate and is independent of that of I injection due to Si0 2 growth. This is reasonable since the V injection should be due to diffusion of Si into Si0 2 in the form of atoms or SiO molecules [7,17]. …”

“…Clearly, an experiment yielding some additional Sb ORD data would now help to provide a further check of the correctness of the model. Moreover, under similar experimental conditions for observing P ORD [17] Sb should show OED, since the model predicts opposite behaviors between these two elements on qualitative basis, see Fig. 1.…”

Bergauf‐Diffusion des Phosphors im Silizium

“…Dmask. unterhalb der durch Si,N, und SiO, maskierten Si-Oberflache) [2] Bei den vorliegenden Untersuchungen ist beabsichtigt, rnit einer Methode, die frei von speziellen Voraussetzungen direkt die Dotandenverteilung ergibt, zu priifen, ob unter den Bedingungen, die etwa fur die Halbleitertechnologie typisch sind, die Phosphordiffusion im Silizium wesentlich durch die oxidationsinduzierten Defekte modifiziert wird.…”