| 摘要 |
1,237,620. Photochromism. INTERNATIONAL BUSINESS MACHINES CORP. 20 Nov., 1969 [23 Dec., 1968], No. 56771/69. Heading C4S. [Also in Division G2] In a method of selectively exposing a radiation-sensitive layer, e.g. to form integrated circuits, a three dimensional mask 22 having a substantial finite thickness and having at least one radiation-transmitting passage is illuminated with coherent light 14, the passage having entrance and exit openings 34, 36 and being internally non-reflective, the magnitude of the resultant wavefront is recorded as a hologram 24, the hologram is illuminated with coherent light 38 and spatially reconstructs a radiation pattern having a three dimensional depth between real images 44, 46 corresponding to the entry and exit 34, 36, the radiation sensitive layer 50 being located between the seal images 44, 46. To compensate for grain irregularities the layer 50 is moved relative to the reconstruction pattern during exposure. Preferably the mask. 22 is opaque apart from one radiation-transparent passage. The radiationsensitive layer may be a photosensitive resist. The "thick" mask 22 may be formed as follows. A photochromic silver halide glass body 54 is darkened by exposure to ultra-violet light of 3000-4000 A. A mask 60, having an aperture corresponding to the radiation-transparent passage, is placed over plate 54 which is then exposed to infra-red radiation of 6000 A or longer, or heat to bleach the photochromic mask in the portion below the aperture. This forms the passage having non-reflective surfaces. To clearly define the entrance and exit of the thick mask 22, relatively thin masks are joined to the thick mask 22.
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