Characterization of nonp devices fabricated at ITCirst Nicola
Characterization of n-on-p devices fabricated at ITC-irst Nicola Zorzi ITC-irst - Trento (Italy) N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
History SMART collaboration End 2003 finalized the layout May 2004 first batch of p-on-n devices on different substrates (FZ, MCz, EPI) Various samples sent for irradiation. August 2004 first batch of n-on-p devices with same layout Some samples sent for irradiation. January 2005 irradiated samples available for test N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Layout 14 + 9 + 6 Test pads including diode, MOS, gated diodes, resistor, etc. 27 MG diodes Area 13. 6 mm 2 die 6 x 6 mm 2 5 (pitch 50 mm) + 5 (pitch 100 mm) Microstrip detectors AC coupled, poly-resistor biased 10 Small MG Diodes Area 2. 3 mm 2 die 4 x 4 mm 2 die 6 x 47 mm 2 N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p batch # sub-type comments 3 FZ 525 p-spray 3 E 12 3 FZ 525 p-spray 5 E 12 3 FZ 200 p-spray 3 E 12 3 FZ 200 p-spray 5 E 12 6 MCz no OG; p-spray 3 E 12 5 MCz no OG; p-spray 5 E 12 N. Zorzi FZ <100> p-type >5000 Wcm 525 mm FZ <100> p-type >5000 Wcm 200 mm MCz <100> p-type >1. 8 k. Wcm 300 mm Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p – IV on MG diodes (1) High dose p-spray Measurements on 3 diodes per 8 wafers Diode current (A) vs Voltage (V) GR current (A) vs Voltage (V) blue=FZ, red=MCz Leakage current ~ 10 n. A/cm 2 Breakdown voltage ~200 -300 V N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p – IV on MG diodes (2) Low dose p-spray Measurements on 3 diodes per 9 wafers Diode current (A) vs Voltage (V) GR current (A) vs Voltage (V) blue=FZ, red=MCz Leakage current ~ 10 n. A/cm 2 Breakdown voltage >1000 V N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p – CV on diodes (1) Measurements on FZ wafers Depletion voltage very uniform at the wafer level. N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p – CV on diodes (2) Measurements on MCz wafers Example of Doping profile from CV measurement Doping concentration lower than n-type MCz (~2 e 12 against 7 e 12) but fluctuations of the same order N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p – CV on diodes (3) Quite high doping variations!! Probably due to fluctuations of the oxygen concentration. N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Microstrip minisensors • AC coupled 1 2 3 4 5 • poly resistor biased 6 7 8 9 10 die ~6 x 47 mm 2 N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Microstrip minisensors measurements probe-card + automatic prober • BL&GR reverse IV • Bias resistors scan (I_tot, Vrev 0÷ 200 V) (R_bias @ 100 V Vrev) • Strip current scan • Capacitors scan (I_strip @ 100 V Vrev) (I_AC @ 20 V Vcap) pitch 50 µm 64 strips N. Zorzi Workshop on p-type detectors pitch 100 µm 32 strips Trento, Feb 28 – Mar 1, 2005
BL & GR I-V reverse currents (1) Bias-line currents @ 100 V high dose p-spray Low dose p-spray FZ wafers N. Zorzi MCz wafers Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
BL & GR I-V reverse currents (2) Bias-line currents @ 200 V FZ wafers MCz wafers high dose p-spray Low dose p-spray • design dependence of voltage handling capability (pitch and …); • low “break” voltage for high-dose p-spray; • substrate dependence? N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Strip current scan (100 V) Low current values on border strips • high- and low-dose p-spray Single strip I-V • 50µm and 100µm pitch • p and n substrates Floating strip potential N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Bias resistor scan (100 V) Single strip I-V 37 squares width=6 µm high dose p-spray Single strip scan Low dose p-spray Single scan uniformity: 0. 2% ÷ 2% N. Zorzi No results available for sensors with low breakdown values Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Defects current-scan: only few sensors AC-scan: ~23% sensors have broken capacitors (mainly 50µm pitch devices) batch or sub problem? No AC-defects are present for p-on-n devices N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
Conclusion Problems on n-on-p production: • non-uniformity of the depletion voltage (MCz subs) • design/p-spray-dose interaction ( p-stop…? ) To be verified: • effectiveness of actual p-spray Samples available for the collaboration. N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
n-on-p batch: samples # sub-type comments 3 FZ 200 p-spray 3 E 12 3 cut wafers 3 FZ 200 p-spray 5 E 12 2 cut wafers 6 MCz no OG; p-spray 3 E 12 3 cut wafers 5 MCz no OG; p-spray 5 E 12 3 cut wafers N. Zorzi Workshop on p-type detectors FZ <100> p-type >5000 Wcm 200 mm MCz <100> p-type >1. 8 k. Wcm 300 mm Trento, Feb 28 – Mar 1, 2005
n-on-p – CV on diodes (3) More measurements on MCz wafers Map of the depletion voltages on three wafers. Quite high doping variations!! N. Zorzi Workshop on p-type detectors Trento, Feb 28 – Mar 1, 2005
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