A comparative analysis of oxidation rates for thin films of SiGe versus Si

Abstract

In order to evaluate the role of Ge as a catalyst or inhibitor for the oxidation process in SiGe, oxidation rates for sub‐100‐nm films of SiGe are examined and compared to previous reports and established models for Si oxidation. Values for the Ge concentration in the pile‐up layer at the oxidation interface are considered as well as the more traditional approach of considering the Ge content in the as‐grown SiGe film. The experimental results presented here indicate that oxidation rates for SiGe closely match those of Si and provide evidence that the presence of Ge in very thin films of SiGe does not lead to enhanced or retarded oxidation rates as compared to Si. This comparative analysis is performed with a focus on oxidation of epitaxial thin films of Si1−xGex in dry O2 at 1 atm at 800, 850, 900, 950, and 1000 °C.

Comparative Analysis of Growth Rate Enhancement and Ge Redistribution during Silicon-Germanium Oxidation by Rapid Thermal Oxidation

“…This mechanism is thus observed for all oxidation conditions used in this study. However, depending on the oxidation temperature, three regimes of evolution of the pile up layer are distinguished and indicated on Figure 10: -For oxidation of Si0.7Ge0.3 at 900°C, the Ge concentration below the oxidation front slightly increases from 46% to 47.5% between 120 s and 540 s. The thickness also increases with time, in agreement with Long et al (11). However, contrary to their results, we found that the Ge concentration below the oxidation front depends on the initial Ge concentration.…”

“…Today, RTO is widely used in the semiconductor industry because it allows reduction of the thermal budget and fine control of the oxide thickness. Few groups studied SiGe oxidation or condensation by means of RTO (5-7) compared to furnace oxidation (8)(9)(10)(11).…”

“…Firstly, SiGe dry oxidation rate remains controversial: some studies report higher SiGe oxidation rates than for Si (6) while some others report equal ones (8) (11). Several mechanisms have been proposed to explain the kinetics of dry oxidation of SiGe but no one has been widely accepted (8) (12)(13)(14)(15).…”

Influence of oxide density on O2 diffusivity in thermally grown SiO2 on Si and SiGe and on oxidation kinetics

“…In spite of the widespread attention that has been devoted to the matter, there is still a lack of consensus regarding the oxidation kinetics of SiGe. A higher oxidation rate, often referred to as the Growth Rate Enhancement (GRE), has been reported for SiGe with respect to Si for dry oxidation [9][10][11] while other works showed no difference [12].…”

Nano-structuring in SiGe by oxidation induced anisotropic Ge self-organization

“…[22][23][24][25][36][37][38] However, conclusions about the role of Ge in determining the oxidation rate vary widely, and the Ge content at the oxidation interface is rarely characterized in a systematic way. 39 Furthermore, except for an early study using (111) oriented material, 40 oxidation of SiGe has been studied with an exclusive focus on (100) material. The orientation dependence of oxidation of Si [41][42][43] may be an indication that SiGe will exhibit similar behaviour, but it is not obvious that SiGe and Si are perfectly synonymous in this respect.…”