Device cross sectioning without losing product wafers

01/01/1999

Device cross sectioning without losing product wafers

Partnering with Siemens, Micrion has developed and introduced its C3D metrology system that for the first time brings device cross sectioning capability onto the fab line, to be done on nonsacrificial product wafers. The hefty $1.6-$3 million price tag is offset by saving product wafers - reportedly up to 40/week at some fabs - that until now were pulled from production for destructive laboratory analysis.

With this system, wafers are temporarily removed from production for in-line analysis. The automated system uses pattern recognition to navigate to a specified test site or sacrificial die, cross-sections the site with a focused ion beam (FIB), performs the desired analysis, and then fills the site with a CVD oxide before returning the wafer to production. Test results can be automatically downloaded to manufacturing databases or yield management systems. Such cross sectioning can be combined with integrated scanning electron and optical microscopes "to provide quick top down and cross-sectional in-fab analysis," says product manager Nick Dawes.

Dawes adds, "FIB has been widely used outside the fab to measure and analyze subsurface features and artifacts, but this requires manual labor and relatively long analysis times. Bringing the technique on-line with total automation, this system bypasses previous challenges associated with measuring small linewidths and multilayer chip structures."

Although Micrion has traditionally built all FIB subsystems in-house, the company - in an atypical process for FIB systems - has relied on well established suppliers in the semiconductor industry for wafer handling, and system automation and control. - P.B.