| 摘要 |
A mask (10) useful in masked ion beam and x-ray lithography is prepared from a polished wafer (12) of crystalline silicon by adding a top layer of silicon (18) having a p-type dopant of an ionic size less than silicon, applying silicon nitride layers to the top (14) and bottom (16) surfaces, selectively etching a window (24) from the bottom surface (16) up to the layer (18) of p-doped silicon to form a doped silicon membrane in tension, etching a pattern in the layer of silicon nitride (20) on the top surface (14), and then etching an exposure pattern partially through the membrane of p-doped silicon. The resulting mask is substantially monolithic, consisting primarily of a single material that does not experience significant internal distortion stresses due to thermal expansion mismatch during later heating and cooling when exposed to an ion beam or x-rays. |
