Tom McMullen Week 8 25/3/2013 – 29/3/2013

LETI wafer thinning project flow Phase 1 IDProject NameOwnerDaysStartEnd 3-Feb10-Feb17-Feb24-Feb3-Mar10-Mar17-Mar24-Mar31-Mar5-Apr12-Apr19-Apr26-Apr 1.0Thin Wafer AssembliesT. McMullen01-Feb30-Sep Week 1Week 2Week 3Week 4Week 5Week 6Week 7Week 8Week PHASE 1 - Layout and mask production, first 2 wafers with microbumps delivered to AdvacamLETI - 3D101-Feb29-Mar LETI accpets CERN proposal 1.1.1Send gds to LETIT. McMullen51-Feb8-Feb Send 2 FEI4b wafers to LETIR. Bates51-Feb6-Feb Confirm step size on wafer and centre ofset variation on waferLETI51-Feb6-Feb Layout and mask productionLETI101-Feb11-Feb Deliverable 1: Microbumb gds files First 2 wafers with micro bumps delivered to AdvacamLETI4912-Feb2-Apr Deliverable 2: First 2 wafers with micro bumps delivered to Advacam Current Deliverable Target not met

Action List Phase 1 and 2 ActionWhatWhoWhenComment 6Further funding for flip-chip processRbates\Cbuttar31/3/2013Richard has confirmed this is all in place 7Bow measurement set-upTMcM31/2/2013 Tool is down and negotiations are ongoing. We may need to find an alternative 8Sensors for flip chippingAll31/3/2013Sensor availablilty for flip-chip process - Meeting rqd 9Assembly probe test solutionTMcM19/3/2013Pobe test solution for flip-chipped assemblies - yield maps 10FEI4B probe card and probe set-upRbates/TMcM19/3/2013FEI4B test solution for assembly testing yeild maps 11Experience with FEI4A probe card set-upRbates/TMcM19/3/2013FEI4A probe card set-up and testing of assemblies on Wentworth 12Source other suppliers of wafer bow measurementsTMcM29/3/2013Ongoing

Highlights and issues  Meeting required to discuss sensor availability for the flip-chip process Amount of sensors for flip-chipping – good statistical analysis required for micro-bump yield – Richard and I have begun discussions on this. ○ List has been made by Richard just awaiting the file IBL TDR bump spec: ○ Pitch = 50um ○ Bump density = 26,880 per ROIC ○ Defect rate < ○ ROIC thickness <200um FEI4b Assembly testing ○ FEI4b probe card required ○ Test equipment/apparatus required ○ Semi-auto testing solution required for assemblies  Meeting set with LETI for an update 25/3/13 Project will be lead by the new 3D manager Meeting to ensure all deliverables are understood Some technical discussions around technology run 2 ○ Grinding and polishing of the wafer backside ○ Discussion around whether LETI de-bonds the first thinning run or we do for the thermal cycling measurements. Further to the meeting held on the 25/3/13 ○ Wafers will be grinded back and then CMP’d to a smooth finish ○ LETI will de-bond the wafers and ship in shipping canisters as they are confident they will be stable at 100um thick. They recommend gentle wafer handling by hand

Highlights and issues (Cont’d)  SMC FSM thermal cycling tool is out of use at the moment. I have given them dates for when the tool is needed and asked for assurance that the tool will be ready by this time. Feedback from SMC is that they hope to have the tool running for when we require it, but have given no guarantees as yet. Sourcing alternatives ○ Southampton only have this ability to 150mm ○ JEMFIRE is another possibility  Masks delivered to LETI and fist 2 wafers for flip-chip with micro-pillars should be available on time.  LETI have an issue processing wafers at the moment as their Argon sputter clean is down in copper PVD tool and will delay the shipment of technology run 1 till the 15 th of April It is essential we run with a sputter etch prior to copper deposition as without it would most likely result in poor electrical contact

Wafer Inventory Wafer #Wafer IDYield (60 chips max)PurposeComment 1VMB8WDHG= 34, y=17, R=8, B=1Full thickness micro-bump testDelivered to LETI. High-yielding die. Micro-bump yeild testing on assemblies 2V6B8WUHG= 43, y=13, R=4, B=0Full thickness micro-bump testDelivered to LETI. High-yielding die. Micro-bump yeild testing on assemblies 3VUAYCRH First technology run. Run 2 Received at Glasgow Wafer thinning to 100microns. Used for thermal cycling bow measurements at SMC. Ship to LETI. Shipped to LETI 4ABPJXGHG=28, Y=24, R=8 First technology run. Run 2 Received at Glasgow Wafer thinning to 100microns. Used for thermal cycling bow measurements at SMC. Ship to LETI. Shipped to LETI 5 Second technology run. Run 3Wafer to be identified and delivered to glasgow 6 Second technology run. Run 3Wafer to be identified and delivered to glasgow 7 Third technology run. Run 4Wafer to be identified and delivered to glasgow 8 Third technology run. Run 4Wafer to be identified and delivered to glasgow 9 Forth technology run. Run 5Wafer to be identified and delivered to glasgow 10 Forth technology run. Run 5Wafer to be identified and delivered to glasgow

Design proposal - Microbumps schape : round shape (32 sides) instead of octogon - Electrical Continuity test proposed -Sacrified dies for alignment Bottom right corner Bottom left corner Proposed tests structures : -Only on 2 alignment chips - 2 Microbumps with 50µm diameter on each metal pad  2 pads on bottom left & 2 pads on bottom right -Test will be done directly on microbumps with microtips Proposed tests structures : -B – pad array will be use for continuity checks for contact between Cu pillars and aluminium pads. This will not affect the functionality of the chip.

LETI wafer thinning project flow Phase 2