Thermal oxidation kinetics of germanium

Conference Dates

May 19-23, 2019


We have studied Ge gate stacks for many years, and demonstrated very interesting properties in Ge [1]. Recently we have published a review paper on Ge from viewpoints of device and process for CMOS applications. Through this study, we have noticed that GeO2/Ge is so different from SiO2/Si. It means that the oxidation kinetics of Ge should be studied carefully and understood correctly, though that of Si is almost understood.

We carried out the oxygen isotope (18O) tracing experiments in Ge oxidation process. Figure 1 shows a comparison between Si oxidation and Ge one, inspected by the SIMS. First, we prepared SiO2/Si and GeO2/Ge oxidized in 16O2, then both were reoxidized in 18O2. SIMS results clearly exhibit a significant difference of 18O profile in the oxides. The result in SiO2/Si system is as expected by the Deal-Grove type kinetics, while that in GeO2/Ge shows rather flat profile of 18O in GeO2 and not 18O accumulation at GeO2/Ge interface. The results demonstrate a significant difference of oxidation kinetics between Si and Ge.

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