IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electronics Tuesday Sessions
       Session EL-TuP

Paper EL-TuP7
Focused Ion Beam Induced Damage in the Transmission Electron Microscopy Specimen of Semiconductor Devices

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Electronic Materials Poster Session
Presenter: N. Kato, IBM Japan
Authors: N. Kato, IBM Japan
H. Saka, Nagoya University, Japan
Correspondent: Click to Email
Focused Ion Beam (FIB) system is indispensable for Cross-sectional Transmission Electron Microscopy (X-TEM) sample preparation, especially when sub-micron spatial accuracy is needed. It is well known that FIB induces damage to the samples. The damage is induced in the etching process as well as in the process of examining the X-section. Earlier study showed that the former does not depend on the etching time or the beam current, and little can be done to reduced the damage other than to use a lower energy FIB. However, the latter varies with the beam conditions, therefore, the examination process can affect the quality of the TEM sample. The purpose of this study is to understand the properties of the damaged layer in order to make a less damaged sample, and exclude the effects of the damage when interpreting TEM images. We studied the damage induced by FIB radiation with smaller current of 1-50 pA at glancing angle of 45 degree, the condition typically used for the examination. We used materials common in semiconductor devices, such as silicon, aluminum, and silicon compounds. We investigated the beam-irradiated surface by X-TEM and Energy Dispersive Spectroscopy (EDS). We found that in the case of crystalline silicon, a few second of beam radiation (< 1 pC/um2) amorphousized the surface. The amorphous layer was 40 nm deep and the gallium concentrates at the outmost 20 nm layer. Radiation of more than a few minutes accumulated a layer consisted of 20 nm carbon rich silicon and 20 nm carbon, silicon and oxide mixture. We found that this layer was made by the re-deposition of the beam-spattered material, which can be reduced by an optimizing the beam condition.