A Novel Technique for Detecting Defects in Ulsi Metallized Systems

Defect location and identification in the metallization systems of ultra-large-scale integrated (ULSI) devices is becoming increasingly important because of the demands of high device density. An understanding of the sources of defects is crucial to the fabrication of submicron devices. Typically, defect identification is accomplished by electrically testing large metal combs and serpents followed by scanning electron microscopy (SEM) investigation. In order to identify metallization defects quickly, we have fabricated a novel device that bypasses the need to electrically probe. This technique utilizes voltage contrast imaging in-situ SEM to locate defects typically found during ULSI device fabrication. While voltage contrast imaging has been used to locate defects in conjuction with externally applied voltages [1], our technique takes advantage of the SEM's own beam as a charging source and makes close resolution (<0.1μm) inspection unnecessary until appropriate. In this way, defects can be located and identified using ∼/20th the time presently required.