Lehman Review April 2000 D. Bortoletto 1 Forward Pixel Sensors Daniela Bortoletto Purdue University US CMS DOE/NSF Review April 12,2000 Progress First engineering run with vendors R&D with BNL Plans

Lehman Review April 2000 D. Bortoletto 2 Forward Pixel Sensors Submissions with two vendors SINTEF(With BteV): 17 wafers delivered 3/2000 CSEM (with BTeV): Layout completed 11/1999 CSEM (Purdue-Zurich-PSI): 3 wafers delivered 2/2000 Development of testing plan Probing studies, irradiation and beam tests Verify design choices and choose substrate: Oxygen enriched Orientation (111) versus (100) Possible re-submission (end of 2000) Final order in 2001 at JHU- BNL, Results New Guard Ring Design and Irradiation with p and n

Lehman Review April 2000 D. Bortoletto 3 LHC environment SIMULATION Radiation environment dominated by pp secondaries L=5  10 5 pb -1   6  cm -2 in six years of operation at r=7 cm

Lehman Review April 2000 D. Bortoletto 4 SINTEF/CSEM submission Wafer layout (Purdue-Fermilab-JHU) Joint submission with BTeV. At least 15 wafers n + /n with p-stops isolation technique on the readout side. 3 wafers will be oxygenated Thickness: 300  m, TTV <8  m Resistivity: k  cm Breakdown voltage: >300 V Leakage 1.5 Vdep: <50 nA/cm 2 Polishing: double sided Passivation: double sided

Lehman Review April 2000 D. Bortoletto 5 history Submission history Nov SINTEF visit FNAL Nov Eurysis Mesures visit FNAL March 1-99 Bids are sent out: Hamamatsu Sintef CSEM CiS institut fur Microsensorik Eurysis Mesures March replay from CSEM and SINTEF

Lehman Review April 2000 D. Bortoletto 6 history Submission history CSEM: March 25, 1999 receive quote for delivery in 20 weeks with no UBM(50.1K) April 28, 1999: PO sent to CSEM Stock availability 300  m,, 1-2k  March 13, 2000: still negotiating final design Sintef: March 25, 1999 receive quote for delivery in 19 weeks with no UBM (82 K) April 28, 1999: PO sent to SINTEF Stock availability 270  m,, 1-2k  October 12, 1999: Approve design March 09, 2000: received 17 Wafers, 3 wafers are oxygenated.

Lehman Review April 2000 D. Bortoletto 7 Sintef/CSEM Submission Goals: Test 150  m x 150  m roc 22x30 pixels arrays Bating on both directions 52x53 pixels arrays 1 2x1 ROCs 1 4x2 ROCs Optimize processing Double open ring p-stop Guard ring design Bias structure for probing Study interpixel capacitance Behavior of unbonded pixel

Lehman Review April 2000 D. Bortoletto 8 Submission Test structures allow to understand both bulk and surface damage: Interpixel resistance structures Interpixel capacitance structures Multiguards diodes (IV & CV) Single guard diodes (IV & CV) MOS capacitors (CV) Gated diodes (IV) Transistors (Subthreshold) Fan Out pixel arrays (Strip ROCs) Interpixel resistance Interpixel capacitance

Lehman Review April 2000 D. Bortoletto 9 Submission Pixel arrays Example 22  34 Reference marks for alignment. Unique ID Scribe line Backside metal grid Redundant bonding/probing pads

Lehman Review April 2000 D. Bortoletto 10 P-stop design Critical choice: Double open ring Pstop: New design Keeps unbonded channels grounded Allows testing before bonding. Reduces inter-pixel capacitance Minimizes Breakdown P-spray (Atlas)

Lehman Review April 2000 D. Bortoletto 11 Baseline design 78  m n-implants surrounded by 2 p-stops rings with openings. Resistive path  O(100K  ). Bump Pad  13  m shifted by 25  m for double column layout

Lehman Review April 2000 D. Bortoletto 12 Guard ring design Requirements Breakdown voltage > 300V Read-out side grounded Voltage drop on guards on the backside Implementation already tested JHU design CMS Si microstrips (tested with 2 vendors) l

Lehman Review April 2000 D. Bortoletto 13 Pixel testing plans Evaluation of the Prototype sensors Probing Irradiation Beam tests Production quality control vendors will control conformance to specification spot check for production stability Readiness of the test centers. Fermilab JHU Purdue

Lehman Review April 2000 D. Bortoletto 14 Prototype sensors Probing Evaluate guard ring design IV curves to measure breakdown voltage Evaluate p-stop design compare IV curves of diodes and pixel devices measure IV curves on different pixel to verify uniform biasing Measure V dep with CV curves before irradiation. After irradiation, measure V dep by using Transient Charge Technique at JHU or signal collection with a pulsed laser at Purdue.

Lehman Review April 2000 D. Bortoletto 15 Purdue-PSI-Zurich wafer Preliminary measurements of diodes and pixels

Lehman Review April 2000 D. Bortoletto 16 Measurements setup

Lehman Review April 2000 D. Bortoletto 17 Preliminary results - CSEM Diodes IV measurements: V breakdown >1000V I/cm 2  68 nA/cm 2 CV measurements: V depletion =155 V

Lehman Review April 2000 D. Bortoletto 18 Preliminary results - CSEM Pixel sensors IV measurements: V breakdown  300V I/cm 2  30nA/cm 2 at 1.5 V dep IV measurements: V breakdown  500V I/cm 2  36 nA/cm 2 at 1.5 V dep #12 #18

Lehman Review April 2000 D. Bortoletto 19 Sintef CMS-BteV wafer

Lehman Review April 2000 D. Bortoletto 20 Preliminary results- Sintef Pixel sensors IV measurements: V breakdown  450V I/cm 2  6 nA/cm 2 at 1.5 V dep IV measurements: V breakdown  300V I/cm 2  6 nA/cm 2 at 1.5 V dep #12

Lehman Review April 2000 D. Bortoletto 21 Preliminary results Leakage current meets specification on 2/3 wafers 50nA/cm 2 100nA/cm 2 Sintef CSEM

Lehman Review April 2000 D. Bortoletto 22 Preliminary results Excellent guard ring design allows diode operation >1000V Pixel breakdown between V according to the design. Further studies are needed to optimize p- stop design.

Lehman Review April 2000 D. Bortoletto 23 Preliminary results Depletion voltage Breakdown voltage Higher for pixel fully covered with metal Breakdown voltage Depletion voltage Pixel sensors

Lehman Review April 2000 D. Bortoletto 24 Probing Prototype Sensors Double sided probing Design of a frame for double sided probing (K.Arndt, Purdue)

Lehman Review April 2000 D. Bortoletto 25 Prototype sensors Irradiation Established record (see JHU results) Irradiate prototype sensors and diodes up to 1, 3, 6 and 10  Proton irradiation at Davis Neutron irradiation at Lowell Irradiation of bump bonded sensors at CERN Beam tests CERN Summer 2000

Lehman Review April 2000 D. Bortoletto 26 Production sensors The test centers will: register sensors in data base perform optical inspection cross check quality tag defects check production stability Leakage current measurement at fixed bias on 5% of wafer

Lehman Review April 2000 D. Bortoletto 27 Readiness of the test centers Test centers: JHU: manual probe station Purdue: semiautomatic probe station Fermilab: several probe stations Conformance: Stability of measurement was checked in all locations. Good agreement was obtained on IV and CV on test diode from BNL. Personnel: Purdue: D. Bortoletto, G. Bolla, 2 graduate students and undergraduates JHU: Chih Yung Chien and Hyosung Cho Fermilab: Simon Kwan

Lehman Review April 2000 D. Bortoletto 28 R&D Sensors, JHU - BNL New guard ring design Guard ring on the n + side replaced by a wide n + implant Irradiation sources Proton (24GeV) up to 1  cm -2 at PS Neutron (1MeV equivalent) up to 1  cm -2 at Univ. of Massachusetts, Lowell

Lehman Review April 2000 D. Bortoletto 29 V Distribution over Guard Rings Non-irradiated Oxygen enriched detector Neutron-irradiated Oxygen enriched detector

Lehman Review April 2000 D. Bortoletto 30 Full Depletion V vs. Fluence Neutron irradiation Proton irradiation

Lehman Review April 2000 D. Bortoletto 31 Goal FY2001 Prototype sensors are available Optimize sensor design Finalize testing and evaluation plan Second submission by the end of 2000 Select final sensor design Order production sensors in March 2001