Methods and apparatuses for trench depth detection and control
AssigneeLam Research Corporation
InventorRandall S. Mundt
Life of this patent
Estimating the term…
Abstract
An inventive method for optically detecting a trench depth in a wafer is disclosed. The method includes detecting a first maxima in the intensity of a multi-wavelength light source, a portion of the light being reflected from the top trench surface of a wafer. A second maxima is then detected in the intensity of the multi-wavelength light source, a portion of which being reflected from the bottom trench surface of a wafer. The method further includes determining a maxima peak difference between the first maxima and the second maxima, wherein the trench depth corresponds to the maxima peak separation. The invention provides a robust, cost effective method for trench depth detection.
Claims6
A system for optically detecting a trench depth, the system comprising:
- a multi-wavelength light source suitable for applying multi-wavelength light to a portion of a wafer;
- and
- a light detector suitable for detecting multi-wavelength light from the light source, wherein the light detector is configured to detect:
- a first maxima in an intensity of multi-wavelength light, a portion of the multi-wavelength light being reflected from a top trench surface;
- reflector location corresponds to the first maxima;
- and
- a second maxima in an intensity of multi-wavelength light, a portion of the multi-wavelength light being reflected from a bottom trench surfaces, reflector location corresponds to the maxima;
- wherein a maxima peak separation between the first maxima and the second maxima corresponds to the trench depth.
Dependencies are inferred from the claim text.