PFTLE 22 High ThroughputLaser Drilling for 3D IC TSV *

PFTLE 22 High ThroughputLaser Drilling for 3D IC TSV *

There will be a major presentation by XSil at the upcoming IMAPS DevicePackaging meeting in Phoenix in March. In keeping with SemiconductorInternationals goal of getting you all the leading edge 3D information as soonas possible in this Perspectivesfrom the Leading Edge blog, I”ll give you a taste of what to expectin the following paragraphs.

  Without question the author / presenter Alexey Rodin is one of theworld experts in using lasers for 3D TSV processing. We have previously notedthat Alexey and XSil were making some significant advances in laserprocessing  with vias down to 10 microns now possible (Perspectives From the LeadingEdge – “Going Vertical in Whitefish” – Sept 9th 2007). Being maskless,the laser process obviously eliminates PR coat, expose, develop and stripprocessing The laser process also naturally produces sloped sidewalls which aremuch more conducive to barrier and seed layer deposition. In addition bycontrolling the laser pulses one is able to “drill” through oxide and nitridelayers as well as Al, Cu, Ni and Ti metallizations. Initial announcements frommemory manufacturers like Samsung have indicated that they are looking long andhard at such laser processing.

  This March Alexey will show results from the X300V Ultra productiontool showing that the laser drilling process is insensitive to via position onthe wafer and via depth uniformity across a 300 mm wafer is currently +/- 4% and they areimplementing controls so that this approaches +/- 1% in
the future. It will be reported that Si removal rates exceeding 20 um per laserpulse are now possible. This translates into 17K vias per minute for a 300 mm wafer with 657 die with 100 (20um dia x 60 um deep ) vias per die ( i.e 15 wafers per hour) …or…53k vias ( 15um dia x 50 um deep) vias per minute for a 300 mm wafer with 1000 vias per die (4-5 wafers per hour).

  R&D is currently going on for vias in the 4-6 um diameter rangefor DRAM and logic applications. So far they have been able to achieveexcellent results by proper opto-mechanical tool design.  

For more dertail on these very exciting results attend Alexeys session inthe IMAPS Device Packaging meeting. For more of the latest information on 3D ICintegration stayed linked to Perspectives from the Leading Edge…..