Abstract

In the photolithographic process, presently employed for the production of integrated circuits, sets of correlated masks are used for exposing the photoresist on silicon wafers. Various sets of masks which are printed in different printing tools must be aligned correctly with respect to the structures produced on the wafer in previous process steps. Even when perfect alignment is considered, displacements and distortions of the printed wafer patterns occur. They are caused by imperfections of the printing tools or/and wafer deformations resulting from high temperature processes. Since the electrical properties of the final integrated circuits and therefore the manufacturing yield depend to a great extent on the precision at which such patterns are superimposed, simple and fast overlay measurements and flatness measurements as well are very important in IC-manufacturing. A simple optical interference method for flatness measurements will be described which can be used under manufacturing conditions. This method permits testing of surface height variations by nearly grazing light incidence by absence of a physical reference plane. It can be applied to polished surfaces and rough surfaces as well.

© 1978 Optical Society of America

Mapping of optical surfaces with quarter wavelength fringes

G. Makosch and W. Jaerisch
Appl. Opt. 17(5) 744-747 (1978)

Optical Contour Mapping of Surfaces

W. Jaerisch and G. Makosch
Appl. Opt. 12(7) 1552-1557 (1973)

Interferometric Flatness Testing of Nonoptical Surfaces

J. D. Briers
Appl. Opt. 10(3) 519-524 (1971)

Surface roughness measurement using dichromatic speckle pattern: an experimental study

Hitoshi Fujii and John W. Y. Lit
Appl. Opt. 17(17) 2690-2694 (1978)

Optical field mapping using single-mode optical fibers

Michitomo Iiyama, Takeshi Kamiya, and Hisayoshi Yanai
Appl. Opt. 17(12) 1965-1971 (1978)