The HGTD: A SOI Power Diode for Timing Detection Applications Work done in the framework of RD50 Collaboration (CERN) M. Carulla, D. Flores, S. Hidalgo, D. Quirion, G. Pellegrini IMB-CNM (CSIC), Spain
Outline 1. Introduction and LGAD Conept 2. Basic HGTD Structure and Operation 3. HGTD and CT-PPS Simulation and optimization 4. Layout and Process Technology 5. First Electrical and Radiation Hardness Performance 6. Conclusions
ATLAS Experiment ATLAS Experiment (CERN) proposes UFSD for future calorimeters as a technical option for the High Granularity Timing Detectors (HGTD) implemented with semiconductors. 2
TOTEM Experiment CMS-TOTEM are considering UFSD to be the timing detectors for the high momentum - high rapidity Precision Proton Spectrometer (CT-PPS) 3
LGAD (Low Gain Avalanche Detectors) are based on Power PiN diodes with an additional P-type diffusion to provide multiplication (gain). Suitable for fabrication of microstrip or pixel detectors which do not suffer from the limitations normally found in avalanche detectors. Core Region Uniform electric field, high enough to activate impact ionization (multiplication) Termination High electric field confined in the core region LGAD Basic Operation Proportional Response (linear mode operation) Good efficiency and spectral range Gain/V BD trade-off Thin detector integration Better S/N ratio (true for small cell volumes and fast shaping times)
Why 50 µm Thick LGAD? 300 µm LGAD with small gain (5-10) is a sensor that maintains similar noise levels than APD, avoiding readout front-end saturation & pile-up effects. Thin substrates (50 µm) reduces the Bulk Radiation Effects and decreases the charge collection time. Thin LGAD = Ultra Fast Silicon Detectors (UFSD) P N N + P - Multiplier Junction Overlap Collector Ring P + N N + 5
High Granularity Timing Detector (HGTD) Pixels of 3x3 mm 2 and 2x2 mm 2 High Resistivity P-type 50 µm SOI Wafers Also trying with 50 & 75 µm Epitaxial Wafers Core Termination 6
CMS-TOTEM Precision Proton Spectrometer (CT-PPS) CT-PPS Sensor Geometry Core Termination Asymmetric design. Segmented according to the hit density distribution Area = 12 mm X 6 mm Thickness = 50 µm Slim edge of 200 um on the side facing the beam Gain ~ 15 Radiation Hard 7
Electrical Performance Simulation (Dose = 1.8 10 13 cm -2 ) Core @ 140V V FD < 40V @ 140V Termination 8
MIP and Gain Simulation T = 295ºK Dose = 1.9 10 13 cm -2 T = 295ºK T = 253ºK Dose = 1.9 10 13 cm -2 T = 253ºK 9
C A2 HGTD CT-PPS Detectors (Mask Design) A1 A2 D B2 B1 B2 C A1 = 8x8 matrix, 3mm pad, LGAD B1 = 8x8 matrix, 2mm pad, LGAD A2 = 4x4 matrix, 3mm pad, LGAD B2 = 4x4 matrix, 2mm pad, LGAD A3 = 2x2 matrix, 3mm pad, LGAD B3 = 2x2 matrix, 2mm pad, LGAD A4 = 2x2 matrix, 3mm pad, PIN B4 = 2x2 matrix, 2mm pad, PIN C = CT-PPS D = TOTEM detector Different diodes and test structures. C A3 A3 A4 B3 B3 B4 C D D Core HGTD 10
Wafers # 10 SOI HPR 50 µm 3 FZ HRP 285 µm 1 Dummy (gluing test) 14 W3-W12 W1; W2 & W14 W13 Multiplication Summary of Processed Wafers Ion Energy (kev) Dose (atm/cm 2 ) Wafer B 100 1.9 10 13 W1-W2; W5-W10 B 100 1.8 10 13 W3 & W4 B 100 2.0 10 13 W11 & W12 - No Multiplication No Multiplication W14 W6 and W10 broken during fabrication 8 SOI wafers + 3 FZ 285 µm wafers + 1 dummy wafer ready for testing Epitaxial wafers (50 and 70 µm) still in process 11
First 50 µm SOI Detectors (HGTD) LGAD HGTD Run Basic Information: Cnm827 Mask Set 8 Mask Levels 100 Technological Steps Double Side Process Electron Collection P-Stop Surface Isolation JTE Termination Peripheral Collector Ring Pixel Detectors (2x2, 4x4, 8x8) Pad Detectors Detectors for Timing Applications Test Structures (Process Quality Control) 12
First 50 µm SOI Detectors (HGTD) Back Surface Front Surface Guard ring pad Back-side wet etch opening HGTD Aluminium reaches the back side contact Passivation opening CT-PPS Slim Edge 13
Connection to Front-End Electronics Pixel = 3 x 3 mm 2 High Resistivity P-type 50 µm SOI Wafers Guard Ring Pad Passivation Opening FE Glue PCB Glue N+ P+ Al Al 3000 µm 30 µm P-stop P++ Al P- SiO2 50 µm 300 µm Silicon Wet Etching Back-Side Contact Calice Si-W Calorimeter Concept
First Measurements: I(V) Characteristics T=21ºC Simulation LGAD Pads PiN Diodes
First Measurements: I(V) Characteristics T=21ºC simulation 16
First Measurements: C(V) Characteristics on Pad HGTD Dose 1.8 10 13 cm -2 Dose 1.9 10 13 cm -2 1/C² (F -2 ) V FD ~40V 1/C² (F -2 ) V FD ~40V Dose 2.0 10 13 cm -2 1/C² (F -2 ) V FD >40V 1/C² (F -2 ) 40 V ~30 V Geometry Factor
First Measurements: I(t) Stability Experimental data show a good current Stability in reverse mode (Between 1.5 and 2.0 na)
Measurements Conditions: Devices: - W5_LGA32P (PIN) - W5_LGA45 (Dose 1.9 10 13 cm -2 ) - W5_LGA81 (Dose 1.9 10 13 cm -2 ) Min Voltage = 50 V Max Voltage = 250 V Step = 10 V Laser: Infrared Illumination: Front side Attenuation: 69% Frequency: 1kHz Gain Values: 2 @ 50 V 12 @ 200 V 25-35 @ 225 V First Measurements: TCT Gain
Conclusions Thin LGAD detectors optimised for fabrication on 50 µm SOI wafers Detectors working as expected from simulation: Voltage capability in the range of 250 V Full depletion voltage in the range of 40 V Time resolution less than 2 ns Linear gain in the operating reverse voltage range (50 200 V) Time stability of the reverse current (2 na) Measurements of radiation hardness and timing capability in progress Technological solutions to minimise the gain degradation due to high fluence radiation under study 20
Thank you! 21
Summary of LGAD Activities at IMB-CNM Clean Room No. Run Tipo # Wafers PiN Waf Mask Set P-Well Drivein Implant Mask Year 5176 1 st APD 8 - CNM 458 3 Doses Long Photoresist 2010 5646 2 nd APD 9 2 CNM 458 6 Doses Short Photoresist 2010 5730 3 rh APD 4 2 CNM 458 2 Doses Short Oxide 2011 5870/5883 4 th APD 4 - CNM 458 2 Doses Short Oxide 2011 5944/5982 5 th APD 5 1 CNM 458 3 Doses Short Oxide 2011 6474 1 st LGAD 11 1 CNM 652 8 Doses Short Oxide 2012 6884/6951 2 nd LGAD 13 1 CNM 652 3 Doses Short Oxide 2013 6984/7062 3 th LGAD 7 1 CNM 652 3 Doses Short Oxide 2013 7509 4 rh LGAD 7 1 CNM 761 3 Doses Short Oxide 2014 7735 1 st Gallium 3 - CNM 761 3 Doses Short Oxide 2014 7782/8642 1 st 200 µm 10 - CNM 761 5 Doses Short Oxide 2014 22
Summary of LGAD Activities at IMB-CNM Clean Room No. Run Tipo # Wafers PiN Waf Mask Set P-Well Drivein Implant Mask Year 7859 5 th LGAD 6-8373 1 st SOI 6 4 2 8533 1 st ilgad 6+3 (Ga) - 8622 6 th LGAD 6+3(Ga) - CNM 761 CNM 784 CNM 809 CNM 761 3 Doses Short Oxide 2015 1 Dose Short Oxide 2015 2 Doses Short Oxide 2015 2 Doses Short Oxide 2016 9088 1 st SOI 50 µm 14 1 CNM 827 3 Doses Short Oxide 2016 Good R&D mainly financed by Spanish research project and partially by CERN RD50 collaboration Under electrical testing Still in process Calibration run 23
1 CURRENT MAP AT: 100 V 2 3 4 5 6 7 8 9 10 LGAD, 300 µm Substrate Yield improved in new fabrications, good repeatability Low leakage current and high breakdown voltage. 1 CURRENT MAP AT: 100 V 2 3 4 5 6 7 8 9 10 A 0,92 ##### ##### 0,24 0,19 0,24 A 3,96 ##### ##### 0,25 0,27 0,34 B ##### 0,26 5,64 ##### 0,26 0,27 B ##### 0,29 1,20 2,40 0,21 0,23 ##### 0,26 C 6,11 100000,00 100000,00 ##### ##### 0,23 0,30 8,04 0,26 C 3,73 2977,08 147,33 1,30 ##### 0,23 0,27 0,72 ##### ##### 0,59 ##### ##### D 1,39 1,08 1,13 ##### 0,18 0,18 0,18 0,19 0,19 0,17 0,79 0,37 2,50 1,45 0,40 3,09 1,65 D 2,04 1,16 1,07 6,05 0,15 0,15 0,14 0,17 0,18 0,18 ##### 0,47 0,72 ##### 0,55 ##### 0,22 E 3983,86 18698,90 27860,60 ##### 0,26 0,21 ##### 0,73 0,85 2,89 0,38 0,77 0,26 E 3,50 5,00 4,37 2,33 0,18 0,16 ##### F 0,48 0,29 4,79 9876,18 5061,10 ##### 80,91 0,31 0,26 F 2,57 347,50 960,66 #### 1,31 ##### 0,29 G 6,37 32691,70 29937,10 127,98 0,90 0,81 0,28 ##### G 2,59 3,31 8,39 0,88 0,81 2,30 H ##### ##### 0,20 0,28 ##### 0,25 H ##### 0,65 0,20 0,30 3,75 0,30 ##### ##### 0,23 0,26 I 5,56 1000,00 1000,00 ##### ##### 0,45 ##### 0,19 0,27 I 2,75 9842,66 10627,00 ##### ##### J ##### ##### ##### ##### ##### ##### J ##### ##### ##### 0,35 0,30 0,43 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Unidades 1,00E-08 A Units 1,00E-08 A 0 1 2 5 10 20 50 100 200 500 1000 na scale o 2016 0 1 2 5 10 20 50 100 200 500 1000 24