Atsushi Miyaki

Observation of basal plane dislocation in 4H-SiC wafer by mirror projection electron microscopy and low-energy SEM

Basal plane dislocation (BPD) with dislocation lines in shallow areas near the surface in 4H-SiC epitaxial wafer was observed by mirror projection electron microscopy (MPJ) and low-energy scanning electron microscopy (LE-SEM). A contrast of dislocation line of BPD appeared in a MPJ observation as gradually weakened dark line toward the upper stream of offcut of wafer, and the contrast almost agreed with the LE-SEM image taken at the same BPD by not a morphology-sensitive imaging method but a potential-sensitive imaging method. Thus an origin of the contrast corresponding to BPD in MPJ is considered to surface potential change due to charging on dislocation line. MPJ observation can gives a BPD image with same quality as a potential-sensitive image by LE-SEM, in extremely short time and damage-and contamination-free condition at no electron irradiation on wafer.

A Study of the Behavior of SE and BSE in UltraLow Landing Voltage Condition

In the study, we set our motivation to consider the mechanism to explain such an interesting phenomena particularly happened at the ultra low voltage situation. At first we gathered a set of SE and BSE images simultaneously at ultra low voltage condition from various kinds of specimen. Second, we compared the SE and BSE image to investigate the difference. A simulation results by CASINO [3] was also applied for the theoretical consideration. In the study the recent cold FE-SEM (Hitachi SU8000) is used. The SEM is offering the SE/BSE filtering capability even at ultra low voltage condition as shown in Fig.1.

Observation of a Latent Scratch on Chemo-Mechanical Polished 4H-SiC Wafer by Mirror Projection Electron Microscopy

A latent scratch which is an extremely shallow scratch induced on a SiC wafer during chemo-mechanical polishing (CMP) has been investigate by mirror projection electron microscopy (MPJ), low-energy scanning electron microscopy (LESEM), atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM). The latent scratch, which is difficult to detect by using optical microscopes, was easily visualized by MPJ as a high contrast dark line. The morphology of detected latent scratch is less than 1nm in depth and about 30nm in full width at half depth by AFM evaluation. The STEM observation revealed the latent scratch was accompanied two dislocation arrays. One contains loop-like dislocations and the other contains spiky dislocations, both lying in the wafer at a few ten nm in depth.

Low voltage, high resolution SEM imaging for mesoporous materials

Mesoporous silicas (MPSs), which possess highly ordered structures with a pore size of 2–15 nm, must be widely applied to catalysts, adsorbents, membranes, and sensors. Direct SEM observation of MPSs provides detail information on the external and internal structures, though it consistently faces charge-up problems of insulating silica frameworks. Several skills such as choosing low resistance substrate or replica method succeed to avoid charge-up phenomena [1]. In this contribution, high resolution, direct SEM imaging of MPSs is tried under the condition of low voltages. A cold FEG SEM, which employs the snorkel type objective lens, retarding device [2] and E cross B (ExB) filter [3] for detecting secondary electron (SE) are used for this study.