Process for measuring overlay misregistration during semiconduct

Details Process for measuring overlay misregistration during semiconduct Process for measuring overlay misregistration during semiconduct

1993-03-03

1995-08-01

Hille, Rolf

Optics: measuring and testing

By polarized light examination

With birefringent element

356358, 356400, 356401, G01B 902

Patent

active

054384133

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 attribute and the processing layer including the target attribute.

REFERENCES:
patent: 4355899 (1982-10-01), Nussmeier
patent: 4818110 (1989-04-01), Davidson
patent: 5017011 (1991-05-01), Lisson et al.
patent: 5112129 (1992-05-01), Davidson et al.
patent: 5258821 (1993-11-01), Doggett et al.

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