Total Dose Dependence of Oxide Charge, Interstrip Capacitance and - - PowerPoint PPT Presentation

Total Dose Dependence of Oxide Charge, Interstrip Capacitance and Breakdown Behavior

• f sLHC Prototype Silicon Strip Detectors and

Test Structures of the SMART Collaboration

• H. F.-W. Sadrozinski, C. Betancourt, R. Heffern, I. Henderson, J. Pixley, A. Polyakov, M. Wilder

SCIPP, UC Santa Cruz

• M. Boscardin, C. Piemonte, A. Pozza, S. Ronchin, N. Zorzi

ITC-irs G.-F. Dalla Betta DIT, Università di Trento

• M. Bruzzi
• Dipt. Energetica, Univ. of Florence
• A. Macchiolo

INFN Florence

• L. Borello, A. Messineo

INFN Pisa Donato Creanza INFN Bari

Structures Investigated

Type Dimension Measurements Frequency MOS Capacitor Circular Area =3.14mm2 C-V 10 kHz Capacitance TS Length = 1.15 cm Pitch = 50, 100 um Implant = 15, 25 um Poly width = 10 um Metal = 23, 33 um Cint-V C-V i-V ~ 1 MHz 10 kHz n.a. SSD Length = 4.46 cm Pitch = 50, 100 um Implant = various Cint-V C-V i-V ~ 1 MHz 10 kHz n.a.

Wafers Investigated

Wafer Type Wafer # Thickness [um] P-spray Dose [cm-2] SSD / TS / MOS n FZ W1254 n.a. TS, MOS p FZ W084 200 5*1012 TS, MOS p FZ W014 200 3*1012 SSD p FZ W037 200 5*1012 SSD p MCz W044 300 3*1012 , no passivation TS, MOS p MCz W253 300 5*1012 , no passivation TS, MOS p MCz W066 300 3*1012 , no passivation SSD p MCz W182 300 5*1012 , no passivation SSD

SSD Investigated

SSD Substrate P-spray Dose [cm-2]. Pitch (μm) # strips Implant Width (μm) Poly Width (μm) Metal Width (μm) 14-5 FZ 200 3*1012 50 64 15 10 27 14-8 FZ 200 3*1012 100 32 35 30 43 37-5 FZ 200 5*1012 50 64 15 10 27 37-8 FZ 200 5*1012 100 32 35 30 43 66-8 MCz 3*1012 100 32 35 30 43 182-5 MCz 5*1012 50 64 15 10 27 182-8 MCz 5*1012 100 32 35 30 43

Device Preparation and Irradiation

Shield Bonded/Not bonded (W253 210 krad)

1 2 3 4 5 100 200 300 400 500 600 700 Bias Voltage [V] Cint [pF] W253 L 3-4 NOT bonded 100 um w253 L 5-6 bonded 100um W253 L 3-4 NOT bonded 50 um W253 L 5-6 bonded 50 um W253 L 3-4 NOT bonded 50 um W253 L 5-6 bonded 50 um

SSD (W037) vs. Test structure (W084 R 3-4) 1 2 3 4 5 6 7 8 9 10 20 40 60 Bias Voltage [V] Cint for 1.16 cm [pF]

W084 50 um 37.pre-rad w084 50 um bonded

UCSC 60Co source 3.15 kRad/hr TS Un-bonded and unbiased except to shield Mini-SSD bonded to shield. Ratio between mini-SSD and T.S. =1.2 (3 pairs vs. 1 pair) T.S. Pre-rad: Large difference between shield bonded and un-bonded T.S. Post-rad: No difference between shield bonded and un-bonded Expect substantial annealing with unbiased devices.

MOS Cap

Doping Density Nd, Flatband Voltage FBV, Oxide Charge Qox

MOS C-V p high-dose p-spray MCz W253 T1-1

124 126 128 130 132 134 136

• 100
• 50

50 100 150

Bias Voltage [V] Capaictance [pF]

pre-rad 210 kRad

FBV = 3V Qox = 1*1011 FBV = 65 V Qox = 1*1012

Flatband Voltage FBV vs. Dose

FB Voltage W084 T1-2&T1-6 p FZ HPD

20 40 60 80 200 400 600 800 Dose [kRad] FB Volatge [V]

W084-T1-2 W084-T1-6

FB Voltage W253 T1-1 & T1-7 p Mcz H DP

20 40 60 80 200 400 600 800

Dose [kRad]

FB Volatge [V]

W 253 T1-1 W 253 T1-7

FB Voltage W044 p MCz LPD

20 40 60 80 100 200 300 400 500 600 700 800 Dose [kRad] FB Volatge [V] W044-T1-7 W044-T2-4 W044-T1-3 W044-T3-2 W044-T3-2 W044-T2-1 W044-T3-1

FB Voltage W1254 T1-8 n FZ

50 100 150 100 200 300 400 500 600 700 800 Dose [kRad] FB Volatge [V]

Oxide Charge Qox vs. Dose

Qox W084 T1-2 & T1-6 p FZ HPD

0.0E+00 5.0E+11 1.0E+12 1.5E+12 2.0E+12 200 400 600 800 Dose [kRad] Qox

W084 T1-2 W084 T1-6

Qox W253 T1-1 & T1-7 p Mcz HDP

0.0E+00 5.0E+11 1.0E+12 1.5E+12 2.0E+12 200 400 600 800

Dose [kRad]

Qox

W253 T-1 W253 T1-7

Qox W044 p MCz LPD

0.00E+00 5.00E+11 1.00E+12 1.50E+12 2.00E+12 100 200 300 400 500 600 700 800 Dose [kRad] Doping Conc W044-T1-7 W044-T2-4 W044-T1-3 W044-T3-2 W044-T3-2 W044-T2-1 W044-T3-1

Qox W1254 T1-8 n FZ

0.0E+00 1.0E+12 2.0E+12 3.0E+12 200 400 600 800 Dose [kRad] Qox

Mini-SSD and Cap T.S.:

Breakdown Voltage, Leakage current, Cint vs. Dose

High dose p-spray breaks down much easier

Mini-SSD and Cap T.S.:

Breakdown Voltage, Leakage current, Cint vs. Dose

Voltage Range 2: region between col. is fully depleted ⇒ depletion proceeds

• nly towards the back

(almost like a planar diode)

full depletion ~200V depletion width of ~350µm Voltage Range 1: region between col. is not fully depleted ⇒ large capacitance full dep. between columns ~ 7V

Mini-SSD and Cap T.S.:

Breakdown Voltage, Leakage current, Cint vs. Dose

The current damage constant is independent of the wafer type, but is a factor two larger for low spray dose (wafer 14 and 66) than for high spray-dose (wafer 37 and 182).

Current @ Depletion vs. Dose

y = 0.0026x + 1.1778 y = 0.006x + 0.7653 y = 0.0028x + 2.3838 y = 0.0068x + 0.7384

0.5 1 1.5 2 2.5 3 3.5 4 50 100 150 200 250 300 350 400 Dose (Krads) I @ V_depletion (uA)

14-8 37-8 66-8 182-8 Linear (37-8) Linear (66-8) Linear (182-8) Linear (14-8)

Cint pre-rad and after saturation (4.45 cm mini-SSD, 100 µm pitch)

Wafers 14 and 37 are FZ, wafers 66 and 182 MCz. Little difference between different wafers, large dependence on the p-spray.

Cint vs. Dose(1.16 cm T.S.)

p MCz high W253 TS L 3-4 50um 12,13,14

1 2 3 4

• 700
• 600
• 500
• 400
• 300
• 200
• 100

Bias Voltage [V] Cint [pF] 70 kRad 210 kRad 305 kRad 305 kRad + 3 days pre-rad( 4,5,6

Little dependence of wafer type, i.e. MCz and FZ behave the same, but dependence on p-spray dose. Ntype increases with dose.

p FZ high W084 TS_R1-2 50um

1 2 3 4

• 700
• 600
• 500
• 400
• 300
• 200
• 100

Bias Voltage [V] Cint [pF]

pre-rad12, 13, 14 70 kRad 12,13,14 140 kRad 12,13,14 280 kRad 12,13,14

p MCz low W044 TS L1 50um

1 2 3 4

• 700
• 600
• 500
• 400
• 300
• 200
• 100

Bias Voltage [V] Cint [pF]

0kRad 140 kRad 270 kRad

n FZ W1254 TS R 5-6 50um 4,5,6

1 2 3 4 100 200 300 400 500 600 700 Bias Voltage [V] Cint [pF] pre-rad 73 kRad 139 kRad 210 kRad 285 kRad

Conclusion Conclusion

MCz and FZ behave similar, Large dependence on p-spray dose.