1. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 1 GLAST Large Area Telescope: Tracker Subsystem WBS 4.1.4 6B: Silicon Strip Detector Receiving and Inspection Alessandro Brez INFN Pisa Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 2 SSD Acceptance Testing LAT Tracker Silicon Strip Detectors go through two levels of testing: –QA provisions: LAT-CR-82 (released); Includes complete plan for verification of the requirements and specifications. –At the manufacturer, Hamamatsu Photonics (HPK): Detector IV curve (leakage current versus bias voltage) Detector CV curve (capacitance versus bias voltage) Test for bad channels (opens, shorts, broken capacitors) Specified in the procurement spec: LAT-DS-11 (released) –At INFN Pisa or INFN Perugia Measure alignment of the cut edges with the lithography (initial all SSDs but later changed to a sampling) Repeat IV and CV curves (all SSDs) Test methods: LAT-TD-85 (released) Dimensional and Electrical Test procedure: LAT-TD-527 (released)

3. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 3 SSD Lot Testing Sample testing done on structures fabricated on the same wafers as the SSDs. See LAT-CR-82 for the details of the plan. At the manufacturer (Specified in LAT-DS-11): –Resistance of poly bias resistor and aluminum electrode –Manufacturing traceability data, including yield By LAT institutes (Hiroshima University): –Radiation tolerance ( 60 Co exposure) –Wire-bonding pads –Coupling capacitance –Capacitor breakdown voltage –Interstrip capacitance –Strip isolation

4. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 4 SSD Receiving & Inspection Detailed procedures are in LAT-TD-527 Carried out on identical equipment operated by –INFN Pisa (in Pisa) –INFN Perugia (in Terni) All work is done in Class-100k clean rooms (actually better) and conforms with the Tracker contamination control plan, LAT-MD-228 Includes Visual, Dimensional, and Electrical Inspections Resulting data are analyzed and compared with HPK data. Data are archived in the Tracker Fabrication Database (MS Access); Summaries are available on the Pisa web site. Nonconforming wafers are set aside for review and possible rejection and negotiation with HPK. Status (March 7, 2003): –5261 SSDs received –4304 tested; 165 reviewed; 38 rejected

5. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 5 Dimensional Inspection Specified dicing tolerance:  20  m Tolerance achieved: <  15  m Moved to sample testing: –3 SSDs from the lot are measured –If any of the 3 show deviations >10  m, then all SSDs in the lot are measured SSD Fiducial Marks Dicing accuracy of the first 1689 flight SSDs

6. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 6 Electrical Tests Individual strips are not contacted (was done at HPK) Measure IV and CV of the detector as a whole to verify HPK results _ + Switch positions: 1=I-V curve 2=C-V curve 2 1 1 2 2 1 _ + KEITHLEY 2410 Source Meter FIXTURE AGILENT 4284 A LCR Meter Bias pad SSD CHUCK

7. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 7 Leakage Current Specification: leakage current <500 nA at 25  C and 150 V

8. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 8 Depletion Voltage (from CV curve) Specification: full depletion at less than 120 V bias.

9. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 9 HPK data statistics: defects analysis bad strips/total strips=72/730752  10 -4

10. GLAST LAT ProjectMarch 24, 2003 6B Tracker Peer Review, WBS 4.1.4 10 Conclusions The SSD dimensional and electrical inspection procedure is well under way (> 38% complete). The results confirm the high quality of the HPK SSDs. The dicing accuracy is more than adequate for our ladder assembly methods, which rely on mechanical alignment. Very few wafers fail the stringent electrical requirements. The second test site (Terni) is fully operational, so there will be no conflict between this activity and other Tracker fabrication activities. The testing is well ahead of (and can easily keep up with) the ladder assembly, so there are no schedule issues with this procedure.