Hard X-ray and fluorescent X-ray detection of alignment marks for precision mask alignment
US4085329A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 3, 1976 |
| Grant date | Apr 18, 1978 |
| Priority date | — |
| Expiry date | May 3, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7076
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.