Probe Mark Analysis
|
Application Overview: Advances in semiconductor manufacturing continually enable more complex semiconductor chips and drive even existing designs to smaller and smaller geometries. This constant trend of miniturization and optimization results in smaller and more powerful finished electronic products like computers and cell phones. However this progression continually presents new and vexing challenges to manufacturers. A critical step in semiconductor manufacturing is the testing of device function at the wafer level. The process uses complex probing equipment to make multiple electrical contacts with the individual devices, often with many devices at a time and spanning multiple die, to confirm their function prior to further processing. Many different probing schemes and types of tip have been used to ensure good contact with the die terminal pads, but the object remains the same: the probe tip should scrub the probe pad to penetrate any oxide or contamination layer to make contact, leaving a mark. The requirement for reproducible ohmic contact must be balanced with the effect of the resulting damage on reliability of wire bonding or the possibility of damage to underlying and increasingly fragile dielectic or other sturctures. |
 |
 |
Depth Control Increasingly Critical As pad pitch decreases, the probe tip size, number of touchdowns, and probe impact force can degrade the wirebond integrity and increase the chance of subsurface damage. Manufacturers must now precisely monitor and characterize probe mark damage to ensure final device reliability and prevent premature failures. Device layer thickness has also been steadily decreasing. With aluminum probe pad thicknesses well below a micron, probe mark depth must now be controlled to less than 400nm. Other probed structures, such as gold pads for DCA, must also be treated gently to preserve their functional properties in the finished device. |
|
Hyphenated Systems 3D Metrology for Probe Mark Depth Control Our Advanced Confocal Technology is the ideal choice for precisely monitoring probe mark depth. Because our technology provides nanometer z sensitivity, we can provide the highly detailed information needed to thoroughly evaluate probe mark characteristics and to troubleshoot probing process excursions. The combination of our advanced automation capabilities with pattern recognition enables rapid, non-contact evaluation of probe mark depth. Limits on probe mark depth and volume may be applied using our systems to quickly and easily alarm on out of specification wafers, allowing the process to be adjusted before further impact on yield occurs. Immediate Advantages: |
 |