04085329 is referenced by 21 patents and cites 4 patents.

The specification describes a process wherein short wavelength or "hard" x-rays (less than about 4 Angstroms) are used to align a semiconductor processing mask with a semiconductor wafer without the requirement for thinning the wafer to permit the x-rays to pass through. These short wavelength x-rays may be obtained from either the continuum x-rays which accompany the "soft" (longer wavelength) characteristic x-rays used for resist exposure, or from a specialized source of hard x-rays. Alternatively, alignment marks may be provided on the surface of the wafer to project alignment-indicative fluorescent x-rays onto an x-ray detector without passing through the underlying semiconductor wafer. A null condition in the intensity of the "hard" x-rays, or the fluorescent x-rays in the alternative embodiment of the invention, which are received at an x-ray detector is indicative of an alignment between a reference mark on the mask and either a reference mark or an opening on the wafer.

Title
Hard X-ray and fluorescent X-ray detection of alignment marks for precision mask alignment
Application Number
5/682432
Publication Number
4085329
Application Date
May 3, 1976
Publication Date
April 18, 1978
Inventor
Paul A Sullivan
Santa Monica
CA, US
John H McCoy
Newbury Park
CA, US
Agent
W H MacAllister
William J Bethurum
Assignee
Hughes Aircraft Company
CA, US
IPC
G01N 21/34
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