Electron beam tools have become the instruments of choice for CD metrology, as well as for defect detection and analysis, because of the many benefits that they offer. As a result of intensive development work the performance of CD-SEMs and related tools has kept pace with the rapid decrease in feature size and the demands for increased throughput. However with the imminent advent of 100nm design rules in 2003 and the requirement for measurement precisions as low as 1nm and the need to detect defects as small as 10nm, it is clear that this situation is changing because the scope for further enhancements in microscope performance is now small. For example, at low beam energies the SEM is now operating at close to the minimum probe diameter set by diffraction, and the physics of electron-solid interactions and of secondary electron generation set a limit to resolution which may be as poor as 3 to 5nm in materials such as resists. Although some incremental improvements can be anticipated, through new technologies such as aberration corrected lenses, and new ultra-bright electron emitters, these advances will not be sufficient to bring the instruments to the levels required for sub-100nm devices and they will certainly not be sufficient to ensure a continued development path to even smaller structure, and the new molecular devices envisioned beyond the end of the road map. Some radical new solutions must therefore be examined. This talk will therefore examine several possible solutions including the use of high beam energies. the replacement of imaging by holographic techniques, the use of energy filtered imaging methods, and the use of point projection microscopes.