SUB-CENTIMETER MICROMACHINED ELECTRON-MICROSCOPE

A new approach for fabricating macroscopic (approximately 10 X 10 X 10 mm3) structures with micrometer accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create four orthogonal v-grooves and an aperture on each 10 X 12 mm die. Precision 308-mu-m optical fibers are sandwiched between the die to align the v-grooves. The fiber is then anodically bonded to the die above and below it. This procedure is repeated to create thick structures and a stack of 5 or 6 die will be used to create a miniature scanning electron microscope (MSEM). Two die in the structure will have a segmented electrode to deflect the beam and correct for astigmatism. The entire structure is ultrahigh vacuum compatible. The performance of a SEM improves as its length is reduced and a sub-cm 2 keV MSEM with a field emission source should have approximately 1 nm resolution. A low-voltage high-resolution MSEM would be useful for the examination of biological specimens and semiconductors with a minimum of damage. The first MSEM will be tested with existing 6-mu-m thermionic sources. In the future a micromachined field emission source will be used. The stacking technology presented in this paper can produce an array of MSEMs 1-30 mm in length with a 1 mm or larger period. A key question being addressed by this research is the optimum size for a low-voltage MSEM which will be determined by the required spatial resolution. field of view, and working distance.