EXAD: A novel electron-beam X-ray absorption method of nondestructive depth measurement for silicon trenches

A novel X-ray absorption method, the Electron-beam generated X-ray Absorption for Depth measurement (EXAD), has been proposed for nondestructive depth measurement of individual submicrometer-wide trenches. This method is based on the phenomenon that X-rays generated at the bottom of a trench by electron-beam exposure decay in intensity while coming out through the inclined path of bulk silicon. An intensity ratio of an X-ray from the bulk surface to that from the bottom is directly proportional to the trench depth. This method has been successfully applied to 1-µm-wide and 5-µm-deep silicon trenches.