Soft X-ray mask alignment system

Claim 2

Process for aligning closely spaced layers in a predetermined superposed relation comprising, placing first and second layers in closely spaced opposing relation, passing soft X-rays through a first one of said layers in a region thereof marked by a soft X-ray absorbing pattern to cast a soft X-ray shadow bombardment pattern on the second one of said layers, intercepting the soft X-ray shadowed radiation with soft X-ray responsive radiant energy emissive material located on said second layer, emitting radiant energy from said material in response to soft X-ray bombardment thereon and passing said radiant energy back through the first layer, and detecting said radiant energy

Claim 3

Aligning process in accordance with claim 1 wherein the radiant energy emissive material emits fluorescence X-rays in response to soft X-ray bombardment.

Claim 4

Aligning process in accordance with claim 1 and further comprising, adjusting the superposed relation of the layers to modify detected radiant energy emission from said second layer to establish a magnitude of emission corresponding to a desired degree of alignment between the superposed layers.

Claim 5

Aligning process in accordance with claim 3 wherein the desired degree of alignment corresponds to maximum radiant energy detection.

Claim 6

Apparatus for aligning at least first and second closely spaced layers in a predetermined superposed relation comprising, means defining an X-ray lithographic substrate as said second layer, means defining a shadow mask marked by a soft X-ray absorbing pattern as said first layer for intercepting and shadowing soft X-rays, means defining a soft X-ray source, means defining a radiant energy detector, the mask and substrate being spaced from each other by a distance of less than 10 - 4 meters and having front faces opposing each other, the source and detector being located behind the mask, said substrate being essentially opaque to soft X-rays, means defining at least one pair of corresponding aligning marks on the front faces of the substrate and mask comprising said soft X-ray absorbing pattern on the mask and radiant energy emitting material on the front face of the substrate.

Claim 7

Apparatus for aligning at least first and second closely spaced layers in a predetermined superposed relation comprising, means defining an X-ray lithographic substrate as said second layer, means defining a shadow mask marked by a soft X-ray absorbing pattern as said first layer for intercepting and shadowing soft X-rays, means defining a soft X-ray source, means defining a radiant energy detector, the mask and substrate being spaced from each other by a distance of less than 10 - 4 meters and having front faces opposing each other, the source and detector being located behind the mask, said substrate being essentially opaque to soft X-rays, means defining at least one pair of corresponding aligning marks on the front faces of the substrate and mask comprising said soft X-ray absorbing pattern on the mask and radiant energy emitting material on the front face of the substrate.

Claim 8

Apparatus in accordance with claim 5 wherein each of the alignment marks comprises an array of parallel stripes.

Claim 9

Apparatus in accordance with claim 6 wherein at least two pairs of alignment marks are provided in the substrate and mask with the stripes of one pair of substrate/mask alignment marks being non-parallel to the stripes of a second pair.

Claim 10

Apparatus in accordance with claim 5 wherein the radiant energy detector comprises a detector of soft X-ray excited fluorescence from the radiant energy emitting material of the substrate aligning mark.