ELECTRON-BEAM TESTING VERSUS LASER-BEAM TESTING

After a short discussion of trends in microelectronics, an overview of modern contactless internal probing techniques is given. Two techniques, electron beam testing and electro-optic sampling, are selected for comparison from the standpoint of the main application, namely CMOS technology. Basic principles are summarized and spatial, temporal and voltage resolution are discussed together with some practical aspects. Electron beam testing has a superior spatial resolution of 0.1-mu-m or better, while external electro-optic sampling can achieve better temporal resolution below 1 ps. Although the voltage sensitivity of the latter can be significantly better, a real quantitative measurement of internal signals has not yet been attained, whereas the former enables exact voltage measurements even at submicron lines. As a practical example, internal measurements at a 7 GHz divider with both probing techniques are compared.