Toshiya Ogiwara

High Depth Resolution Auger Depth Profiling Analysis Using Inclined Holder

Auger electron spectroscopy (AES) combined with argon ion sputtering is widely used for the depth profiling of multilayer structures. In this method, it is very important to measure the depth profile of a specimen with high depth resolution to evaluate the structure of materials precisely. In this work, we have carried out the high depth resolution Auger depth profiling analysis with a very shallow incident angle of argon ion for sputtering using an inclined holder. A schematic view of the shallow angle argon ion sputtering method using an inclined holder is shown in Fig.1. The sample is mounted on a slanted sample holder. The sample surface is inclined over an angle 45° with respect to the base plane. In consequence, the angle between the sample surface normal and the electron beam direction is 45° with independence of the azimuthal rotation [1]. At the same time, the incidence angle of argon ions can be varied from 38.9° to 83.3° by rotating the sample. In this way, the inclined holder enables the very shallow incident angle of argon ion for sputtering to be used. In order to examine efficiency of this method, we have performed Auger depth profiling of a GaAs/AlAs multilayer specimen using the inclined holder. The measured Auger depth profiles of the GaAs/AlAs multilayer specimen using the inclined holder are shown in Fig. 2(a). The incidence angle of argon ions was 83.3°. For comparison, the Auger depth profile measured by the conventional method at the incidence angle of 38.9° is shown in Fig 2(b). The depth resolutions of Ga LMM and Al KLL obtained from Figs. 2(a) and (b) versus the depth from the surfaces are summarized in Fig. 3. The depth resolution is defined by the distance between 16% and 84% (or 84% and 16%) of the intensity change at an interface. The depth profile of Ga-LMM and AlKLL in Fig. 2(a) showed much better the depth resolution compared to that of the conventional method as shown in Fig. 2(b). We applied the inclined holder to the measurement of a Si/Ge multiple delta-layer specimen. The measured Ge LMM Auger depth profile of the Si/Ge multiple delta-layer specimen is shown in Fig. 4. We can observe the Ge mono-layer of the Si/Ge multiple delta-layer specimen using an inclined holder. This method is the practical measurement method utilizing the characteristic of the hemisphere type AES device.

A study of the appearance of Li Kα

Using electron beam excitation, Li K? of insulator samples, such as oxides other than LiF, is impossible, or very hard to detect. Metallic Li, on the other hand, is easy to observe. Therefore, an examination using cluster calculation was carried out. From the calculation results, it was revealed that the Li K? of LiF obtained by our measurement did not correspond to the correct state of Li in LiF. This spectrum might be emitted from the Li atom which was reduced and changed to the metallic state due to the electron beam irradiation. It was also suggested that the existence of the conduction electron at valence might easily cause the dipole transition process for the relaxation of the hole on the shallow core hole. Such a hole is generally relaxed by the Auger relaxation process.

Auger depth profiling analysis using an inclined holder (Extended abstracts book of the International Workshop for Surface Analysis and Standardization '09 (iSAS-09))

We have investigated the high depth resolution Auger depth profiling using an inclined holder. The developed inclined holder enables the very shallow incident angle of argon ion for sputtering to be used. In consequence, depth profiles of Ga LMM and Al KLL from a GaAs/AlAs multilayer specimen showed a much better depth resolution compared to those obtained by the conventional method. We also measured the Auger depth profiles of a Si/Ge multiple delta-layer specimen using the inclined holder and confirmed. A Ge mono-layer can be profiled.

Auger Depth Profiling Analyses of InP/GaInAsP Multilayers

We have investigated the dependence of the depth resolution of Auger depth profiles of InP/ GaInAsP multilayer specimens on the sputtering rate, and the surface roughness caused by the ion bombardment. Ar ions having energies of 1.0 and 3.0kV were used for the sputtering. The depth resolution of the measured Auger depth profiles was improved by increasing the sputtering rate. Thus we obtained, by 3.0kv Ar ion sputtering, excellent Auger depth profiles with constant depth resolution from the outermost surface of the samples. We found that the obtained depth resolutions of the trailing edge group were largely different from those of leading edges in several specimens. We also found that the resulting resolution of Auger depth profiles could be determined by the surface roughness caused by the Ar ion sputtering.