| 摘要 |
<p>A mask (18) for use in ion beam and x-ray lithography is prepared by depositing several layers of silicon-based materials onto a polished single-crystal silicon wafer (24), and then etching the layered structure to form the mask (18). A boron-doped, single crystal, epitaxial silicon layer (22) is first deposited overlying the silicon wafer (24), and the boron-doped layer (22) is partially oxidized on its exposed surface to form a thin silicon dioxide layer overlying the boron-doped layer (22). A layer of amorphous silicon is deposited overlying the silicon dioxide layer, an upper layer of silicon nitride is deposited overlying the amorphous silicon, and a lower layer of silicon nitride is deposited overlying the opposite side of the single-crystal silicon wafer (24). After patterning, a window is etched through the lower silicon nitride layer and into the single-crystal silicon wafer (24), to the boron-doped silicon layer (22). The exposure pattern is etched into the membrane through the upper silicon nitride layer, the layer of amorphous silicon, and the silicon dioxide layer, leaving thick unpatterned areas and thin patterned areas. During use of the mask, ions or x-rays pass through the patterned areas of the membrane, but are absorbed in the thicker unpatterned areas, to produce a pattern of transmitted ions or x-rays on the target.</p> |
