Browse Prior Art Database

Sem-Based Infrared Contamination Detector

IP.com Disclosure Number: IPCOM000039386D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Dacol, FH: AUTHOR [+3]

Abstract

An infrared (IR) detection device can detect contamination on patterned wafers, including product debris, while completely ignoring the intended features of the wafer. The apparatus is based on a conventional SEM equipped for wafer inspection with a LaB6 electron filament, an interlocked wafer loader and a motorized wafer stage. The accessories include a PC to drive the wafer stage and the electron beam sweep coils, and for data collection and manipulation, an A/D converter for data digitization and beam sweep coil voltage input, a graphics monitor for displaying the IR image, and an IR collector/detector/preamplifier assembly. The IR collector/detector is detailed in the figure. The wafer is positioned in the lower focal point of tilted ellipsoidal mirror 2 which has a collection efficiency of greater than 50%.

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Sem-Based Infrared Contamination Detector

An infrared (IR) detection device can detect contamination on patterned wafers, including product debris, while completely ignoring the intended features of the wafer. The apparatus is based on a conventional SEM equipped for wafer inspection with a LaB6 electron filament, an interlocked wafer loader and a motorized wafer stage. The accessories include a PC to drive the wafer stage and the electron beam sweep coils, and for data collection and manipulation, an A/D converter for data digitization and beam sweep coil voltage input, a graphics monitor for displaying the IR image, and an IR collector/detector/preamplifier assembly. The IR collector/detector is detailed in the figure. The wafer is positioned in the lower focal point of tilted ellipsoidal mirror 2 which has a collection efficiency of greater than 50%. The electron beam 3 induced IR radiation from the target is collected and focused onto a 0.1 mm2 cooled InSb detector 4 which is positioned at the upper focal point of the mirror. The detector is connected via a cold finger 5 to a liquid nitrogen dewar 6 which inserts in the microscope chamber. The leads from the detector are protected from stray electrons in a stainless steel bellows jacket 7 and delivered through a hermetically-sealed bulkhead feed-through to the IR preamp/amplifier. The assembly allows unrestricted movement of the wafer in the plane perpendicular to the electron beam direction which intersects with the lower focal point of the ellipse. In practice, the wafer would be introduced to the evacuated SEM chamber via the interlocked wafer loader, positioned in the Z direction at the target focal point, and XY scanned with the motorized stage while the wafer is being swept by the el...