February_EDFA_Digital

edfas.org ELECTRONIC DEV ICE FA I LURE ANALYSIS | VOLUME 24 NO . 1 38 ISTFA 2021 USER GROUP HIGHLIGHTS Anita Madan* and Daminda Dahanayaka,** ISTFA 2021 User Group Chair/Co-Chairs *Independent Consultant, Malta, N.Y. — amadan16@hotmail.com **GlobalFoundries, Malta, N.Y. — daminda.dahanayaka@globalfoundries.com F our in-person User Group sessions were held during the ISTFA 2021 conference at the convention center in Phoenix in November 2021. Despite the COVID-19 travel restrictions, all four user groups had a satisfactory attendance: SOP, Sample Prep, and Contactless Probing and Nanoprobing each had around 40 participants, and FIB about 60 participants. The audiences of all the four user groups enthusiasticallyengaged indiscussingmatters important to themas analysts and shared their knowledge and experience with each other. Participants included analysts fromalmost all major semiconductor companies, tool vendors, and university attendees. The focus of the user groups was to promote audience participation, inter- actions among the attendees, networking, and provide a lasting way to communicate critical issues even after the workshop. Each user group had several invitedmini talks to ignite the discussion around certain focused topics. Feedback from attendees was very positive about the content, format, and level of participation. The audience was encouraged to continue their discussion afterwards in the ASMcommunity discussionboards set up for eachuser group. Following are summaries of the four user groups. ISTFA 2021 USER GROUPS ISTFA 2021 SAMPLE PREP USER GROUP Chair/Co-Chairs: Jim Colvin, Cecile Bonifacio, Kah Chin Cheong, and Nathan Bakken jim@fainstruments.com, cs_bonifacio@fischione.com, kah.cheong@samsung.com , nathan.j.bakken@intel.com T he Sample Preparation User Group discussion was held in-person with approximately 40 attendees. Highlights included the new challenges posed by 3D ICs and thinning/polishing methods such as the chip recombination method, concentrated Ar ion milling, and iterative RST model measurements as an aid for ultra- thinning. Topics included sample prep for PVC, a vendor request for amultimaterial cutting solution, ultrathinning (RST measurements, XeF2 plasma etch), solder bump delamination, and 3D ICs. DamindaDahanayaka fromGlobalFoundries kicked-off the event by welcoming the attendees and briefly intro- ducing the User Group series. KahChinCheong fromSamsungAustinSemiconductor shared a subtitled video presentation about die removal from packaging and avoiding chip edge defects during delayering. Kah described step-wise how to remove a die froma chip-scale-packagewithout damaging the die. The second topic detailed the chip recombination method of using dummy chips, positioned adjacent to edges of inter- est, to prevent rounding/uneven polishing of the edges. NathanBakken fromIntel questioned some small, residual edge effects, which may have been caused by an uneven top surface across the abutting chips. This issue could be mitigated by using a coverslip. Inapre-recordedpresentation, Pawel Nowakowski dis- cussed sample preparation for solder bumps. Mechanical polishing, broad beam ion milling, and planar ion milling were compared. Ion milling was described as being more than 4x faster than mechanical polishing as well as being resistant to shadowing and surface contamination artifacts. Nathan Bakken gave an exciting presentation about 3D ICs, a near-future technology with many sample- preparation challenges. 3D ICs will have metallization on both sides and active transistors on multiple layers. The