New nondestructive method to measure metal film thickness

Xiaodong Wu; Gordon S. Kino

doi:10.1117/12.145454

21 May 1993 New nondestructive method to measure metal film thickness

Xiaodong Wu, Gordon S. Kino

Proceedings Volume 1805, Submicrometer Metallization: Challenges, Opportunities, and Limitations; (1993) https://doi.org/10.1117/12.145454
Event: Microelectronic Processing '92, 1992, San Jose, CA, United States

Abstract

We report here a new, noncontacting, and nondestructive photothermal phase microscope to measure metal film thickness in integrated circuit devices down to 150 angstroms with a 30 angstroms sensitivity. A thermal diffusion wave ranging from 3 - 500 MHz is excited with an intensity modulated laser beam. The wave is reflected by the insulating layer underneath the metal film back to the surface. A second laser beam measures the reflected thermal wave using the fact that the surface reflectance is a function of the temperature. The phase delay between the surface temperature variation and the heating beam modulation yields the thickness of the opaque film. Since the technique uses the phase of the photothermal signal, instead of amplitude, the result is not critically dependent on the surface roughness or tilt of the sample. In addition, the measurement can work with very small pads (3 micrometers X 3 micrometers ).

Citation Download Citation

Xiaodong Wu and Gordon S. Kino "New nondestructive method to measure metal film thickness", Proc. SPIE 1805, Submicrometer Metallization: Challenges, Opportunities, and Limitations, (21 May 1993); https://doi.org/10.1117/12.145454

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