Analysis of submicron defects using an SEM-Auger defect review tool

Abstract

The challenges associated with analyzing semiconductor defects become greater as the device design rule decreases. According to the SIA National Technology Roadmap for Semiconductors. the current metrology requirement for particle analysis is 90 nm with the need to analyze 75 nm particles by the year 2001. These dimensional requirements are beyond the typical capabilities of current SEM/EDX defect review tools. Auger Electron Spectroscopy is a powerful method for measuring the surface composition of localized regions, and has been identified in the SIA roadmap as a primary technique for particle analysis. The ability of a state-of-the-art Auger defect review tool (DRT) to provide secondary electron and high spatial resolution elemental images is particularly effective in characterizing the often complex structure of semiconductor defects. Examples of Auger analysis from defects found at various process steps, on both unpatterned and patterned whole wafers, are shown. These examples highlight the ability of Auger to analyze both thin and laterally small or complex defects.

Microscopy and spectroscopy characterization of small defects on 200mm wafers

“…These two factors; vastly improved spectral resolution and confinement of the signal volume, will greatly extend the usefulness of the SEM/ EDX combination. It has been argued by Auger proponents that EDS runs out of steam below 0.2tam, and that Auger must be used (25). This is certainly not true for micro-calorimetry based EDS.…”

Auger Electron Spectroscopy

“…For example, because of its excellent spatial resolution and nondestructive nature, AES is ideally suited to identify and characterize submicron semiconductor defects (as small as 500 Å) which are beyond the capabilities of conventional methods based on X-ray dispersive analysis tools [61]. An Auger defect review tool (DRT) capable of analyzing 200-mm thick wafers has been developed and evaluated [62][63][64]. Despite the demanding requirements for ultrahigh vacuum, a recent publication has recommended that AES and XPS analysis be moved from laboratory settings to the production line in integrated circuit manufacture [65].…”

“…Because of shrinking device dimensions, AES has recently become a vital tool in the semiconductor industry for process control and failure analysis [60]. For example, because of its excellent spatial resolution and nondestructive nature, AES is ideally suited to identify and characterize submicron semiconductor defects (as small as 500 Å) which are beyond the capabilities of conventional methods based on X-ray dispersive analysis tools [61]. An Auger defect review tool (DRT) capable of analyzing 200-mm thick wafers has been developed and evaluated [62][63][64].…”