Testing Site Qualification

1. Testing Site Qualification • Purpose: • Perform detailed scans of the silicon microstrips to make sure they all work. • Check HPK. • Candidates for Certification: • Kansas State University (KSU) • Stony Brook (SB) • Fermilab

2. Measurements to be Done on All Strips • Measurement Bad Strip • Idiel >10 nA (PINHOLE) • current through the coupling capacitance • Cac > 1.2*mean (OPEN) • coupling capacitance < 0.8*mean (SHORT) • Istrip > 10 nA (LEAKY) • leakage current to a strip • Rpoly > 1.1 MOhm or < 0.5 MOhm • polysilicon resistance • SB measures on strips, KSU on test structures • Rint < 2 GOhm • interstrip resistance • Cint > 4.65 pF (L1) • interstrip capacitance > 5.90 pF (L2)

3. Whole Detector Measurements Done also by Fermilab • CV > 300 V • measure capacitance versus voltage • determine FDV • IV • measure current up to 500 V (L2) > 16 mA at 350V • measure current up to 800 V (L0,1) > 4 mA at 700V • bad strips > 1% Measurement Bad Detector

4. KSU

5. SB

6. Rochester

8. Equipment Item KSU SB Both groups use the matrix to perform multiple tests while only touching each pad once. KSU scans the even and odd pads separately, since the AC pads are staggered. The three probes are used for the AC pad and DC pad of each strip, plus a neighbor AC pad (an additional touch). SB touches AC and DC pads of neighboring strips and completes the scan in pairs. One probe always even, one always odd. This enables interstrip measurements at the same time.

11. Idiel for ELMA sensor L1-010

14. Measurement Techniques KSU SB

15. Measurement Procedures • Repeat obviously bad measurements: • The bias line loses contact: Strip currents approach the total leakage current. • SMU mode problem: Rpoly is infinite and Idiel is very small for all strips. • [Neither of these has caused a problem recently.] • Remeasure bad strips, to see if the problem is a result of bad contact. • If the bad measurement value repeats once, the strip is called bad. • At the end of the scan lift both probes to measure the background and do a two-strip scan. The background values of Idiel, Cac, Istrip, Cint, and Condint are then subtracted from corresponding values for all strips. (We should subtract conductances in measuring Rpoly, but do not bother since the correction is very small.) The background values are generally a small fraction of the bad strip limit.

16. Comparison of Results on Bad Strips So when the measurement repeats, KSU and SB agree.

17. 4 L2 Sensor Comparison Full Depletion Voltage (HPK Method) • HPK and SB are higher than FNAL and KSU? • Search for possible reasons: • SB uses a different LCR meter from KSU and FNAL • SB uses ceramic blocking capacitors in front of our LCR (low f)

18. The SB 130V for L2-77 could be due to a fluctuation, in one value of C, weakness of the HPK method.

19. No Breakdown seen up to 500 V (L2 limit)

26. Number of Bad Strips

27. Conclusions • KSU, SB, and Fermilab sensor probing sites are fully equipped and operational • Equipment has arrived for the Rochester probing site and is currently being setup • Rochester expected to probe inner layer sensors • Site will be certified in similar way as SB and KSU • Bad contacts encountered during probing can be overcome • No outstanding problems • Ready to probe the incoming sensors