Process for measuring overlay misregistration during semiconductor wafer fabrication
US5438413A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 1993 |
| Grant date | Aug 1, 1995 |
| Priority date | — |
| Expiry date | Mar 3, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A process for measuring overlay misregistration during semiconductor wafer fabrication including the use of an interferometric microscope in combination with a camera, a wafer transport stage, and data processing electronics to form an inspection system which can utilize either broadband or narrowband light, and large or small numerical aperture (NA) to develop a series of interference images taken at different Z (vertical) planes relative to the surface under investigation or P (pathlength) positions relative to interferometer arm difference. The data in these planes is then used to calculate the magnitude and phase of the mutual coherence between the object wave and the reference wave for each pixel in the image planes, and synthetic images are formed, the brightness of which is proportional to either the complex magnitude (the Magnitude Contrast Image or MCI) or the phase of the mutual coherence as the optical pathlength (the Phase Contrast Image or PCI) is varied. The difference between synthetic images relating to target attribute position and bullet attribute position are then used as a means of detecting misregistration between the processing layer including the bullet attri…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.