Browse Prior Art Database

Enhancement System Bent Chip Monitor

IP.com Disclosure Number: IPCOM000045229D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Hopper, GS: AUTHOR [+3]

Abstract

The bent chip monitor using direct visual observation of an orthogonally lined grid reflected in the polished backside of a semiconductor wafer is operator sensitive in that operator astigmatism, eyestrain or fatigue impacts the uniformity of inspection results. Such sensitivity is significantly reduced by the use of a TV camera and display unit equipped with telephoto lens and by movably mounting the orthogonally lined grid.

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Enhancement System Bent Chip Monitor

The bent chip monitor using direct visual observation of an orthogonally lined grid reflected in the polished backside of a semiconductor wafer is operator sensitive in that operator astigmatism, eyestrain or fatigue impacts the uniformity of inspection results. Such sensitivity is significantly reduced by the use of a TV camera and display unit equipped with telephoto lens and by movably mounting the orthogonally lined grid.

Light source 5 illuminates grid 4 whose image is reflected in the polished rear surface of chip 1 toward TV camera 6. Chip 1 is conventionally fixed by solder balls 3 on substrate 2. Grid 4 is mounted so that it may be moved by the operator along axes x or y or perpendicular thereto.

The TV camera is equipped with a telephoto lens which is focussed on both the reflected image of the grid 4 and the chip-joined substrate. This focus requirement means a high numerical f stop must be used, as the chip to lens distance is about 1/2 the grid to lens distance.

Moving the grid, either by a Z direction vibration or by X-Y translation, provides a "dancing line" image on the TV screen 7 which enhances the detectability of bent chips. Since the image of the grid is projected on a TV screen, the amount of chip bending can be quantized by a straight edge and ruler. A more elaborate system would involve a terminal with computer-assisted line curvature measurement.

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