SiGe profile inspection by using dual beam FIB system in physical failure analysis

Abstract

A dual beam FIB (Focused Ion Beam) system is widely used in semiconductor construction analysis and failure cause identification. The application of FIB is useful for defect or structure inspection in FA (Failure Analysis) field, but it can not always observe the failure mechanism as insufficient resolution image especially in advanced process products. This restriction will deeply impact the judgment of worst site or real failure site in PFA (Physical Failure Analysis). Although the problem can be overcome by advanced TEM (Transmission Electron Microscope) technology, how can analysts know that the suspected failure site is a real killer or not when looking at the insufficient resolution images? A novel technique IEE (Insulator Enhanced Etch) by FEI company had been applied in FIB system. IEE technology is the combination of FIB and dry etching that allows rapid etching of insulating materials using a halogen compound, XeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (Xenon Difluoride ). XeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> strongly etches silicon so it should be used sparingly to highlight silicon layer. This novel technology provides a good method for better inspection in SiGe process. A familiar problem of SiGe process is SiGe-SiGe bridge, it is difficult to diagnose failure site due to insufficient resolution and bright white line effect. By the IEE technology, the FA analysts can find the real failure site instead of trying TEM inspection directly.