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Date: 4/12/2012 Voxtel Contacts: George Williams Vinit Dhulla Adam Lee Address:

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Presentation on theme: "Date: 4/12/2012 Voxtel Contacts: George Williams Vinit Dhulla Adam Lee Address:"— Presentation transcript:

1 Date: 4/12/2012 Voxtel Contacts: George Williams Vinit Dhulla Adam Lee Address: NW Schendel Ave, Suite 200, Beaverton, OR Voxtel SPAD/SiPM, ROIC, and Multi-channel TDC Technologies

2 Presentation Agenda Voxtel Overview Silicon APD Development AQC Based ROIC Development Hybridization Development Other DOE Related ROIC Development Activity Multi-channel, Reconfigurable Pulse-processing Instrumentation

3 3 About Voxtel Corporate Offices / Voxtel Opto (Beaverton, Oregon) Contract Administration Opto Products Group −InGaAs and silicon photodiodes, avalanche photodiodes (APDs), photoreceivers, and focal plane arrays −Readout integrated circuits (ROICs) for imaging, LADAR, and radiation detection −Single-photon-sensitive detectors and instruments −Electro-Optic systems engineering Voxtel Nano (Eugene, Oregon) Nano Products Group −Colloidal semiconductor quantum dots (PbS, CdSe, InP, SnTe, etc.) −Rare-earth-doped nanocrystals (ZnS, YVO 4, LaF 3, etc.) −Ligand design and custom surface functionalization −Optical up- and down-conversion −Security inks and covert taggants −Nanocrystal-sensitized photovoltaic and photoconductive devices −Continuous flow reactors for nanocrystal/quantum dot synthesis Analytical Facilities

4 Selected Voxtel Products Single-Element InGaAs Photodiodes and APDs Free-Space Coupled Photoreceivers InGaAs Photodiode and APD Arrays Fiber-Pigtailed Photoreceivers Multi-Channel Time Recorder Boards CMOS Readout Integrated CircuitsFocal Plane Arrays for Imaging and LADAR

5 Proposed Detector Arrays & ROIC Standards DETECTORS 50 micron square pixel 1 x 1mm 2 (fiber) and 4 x 4 mm 2 (calorimetry) arrays compatible with face-to-face (f2f) or TSV bonding Back-illuminated for 300nm response ROICs: Matched to SPAD arrays 1 x 1 mm 2 nsec TOF on chip MHz count rates 10s photons dynamic range 4 x 4 mm ps TOF in fabric of SPAD array 1000s photons dynamic range

6 Back-illuminated Silicon Gm-APD Development Implemented at Tower/Jazz Domestic source fine photolithography (0.25µm and 0.18µm) availability of silicon-on-insulator (SOI) wafer options shallow Trench Isolation (STI) and Deep Trench Isolation (STI) double-layer metal-metal (MiM) capacitors availability of a stitching option for large area, photocomposed wafer-scale integration mature and stabile government-funded back-thinning capabiltiy under development we have transistor radiation models Implemented in a commercial, 200mm CMOS fab compatible with monolithic circuit integration compatible with modern 3D wafer stacking technologies (>200mm) Back-illuminated to improve UV-Blue optical response

7 Base Gm-APD Pixel Designs N+/”p+ sinker” junction N+/p-well junction Sinker is a custom p+ implant developed by Voxtel in the Jazz process used to achieve full depletion before junction breakdown used to “focus” high field region and avoid pre-mature edge breakdown N+/p-well junction uses only the standard implants Implemented on SOI wafers Heavily doped p+ implant at BOX interface used to biases substrate STI (shallow trench isolation) / DTI (deep trench isolation) used for (sub)pixel isolation

8 TCAD Models of Gm-APD Pixel Variations Deep Trench IsolationN-well Implanted STI N-well Guard Ring (connected to n+) Multiple Guard Rings

9 Simulated/Measured I-V Curves for Various Doping Levels Used to calibrate Voxtel’s process models with Jazz fab process parameters not published by fabs, they need to be deduced Measured breakdown voltage closely match the simulated values (within 10%) validates the design and control of the custom sinker implant Breakdown voltage is uniform between devices on the same wafer and across different wafers.

10 SiPM Performance

11 Measured Gain/DCR vs. State-of-Art (SOA) Gain sufficient for photon counting (1 p.e. pulse), photon # discrimination, and integration with electronics Initial DCR is higher then desired Not enough experimental data to analyze and fully characterize DCR sources DCR is much better than other CMOS fabricated SiPMs (e.g. RMD) Recent design run includes experimental DCR test structures and design features

12 Digital SPAD Architecture implemented in CMOS Cross section of Jazz Semiconductors thick film SOI processes. custom implants used to optimize the process for fabricating low breakdown Gm- APD designs trench isolation enables isolation of active circuits with the photodetector elements. Demonstrated Digital SPAD features include: active quenching, programmable hold-off timing, threshold detection, photon counting / time-to-digital converter in-pixel APD bias NUC, and integrated fuse

13 35-micron Pitch Digital SPAD Pixel Block Diagram Each pixel features: an active quenching circuit with globally controlled pre-charge and quench timing - 3 rd generation of an AQC design originally developed for Geiger mode (Gm) integrated SRAM with “power down” circuits - enables individual characterization of each pixel in the SPAD array. - used to disable “noisy” pixels across the array, lowering the detector dark counts Quench Time: 5.0 – 900 ns Pre-charge Time: 2 – 12 ns Output Pulse Time: 2 – 10 ns

14 35-micron Pitch Digital SPAD Pixel Layout Layout of Digital SPAD pixel design on a 35-µm pixel pitch An APD was implemented in the monolithic design (upper left hand corner) for test APD fills 47% of the total pixel area In hybrid (wafer bonded) designs, the pixel will be shorted Monolithically integrated APD AQC and quench delay generator Output pulse generator and driver SRAM and power down

15 VX-808 Digital SPAD Testchip will be used to evaluate both APD designs used to re-test s AQC circuits taped out to Jazz Semi. Jan (back May 2012) Pixel array testchip (40 x 40) with 35 µm pixel pitch APD and SiPM test structures

16 Wafer-scale Back-thinning Process

17 Sensor Hybridization (3D Stacking) and Thinning 8” ROIC wafer bonded to matching 6” SOI photodiode wafer. Bonded/Thinned (6” to 8” wafers) Mesa Etch/Pad Opening Bonded Device after bonding and thinning, detector mesas are formed (grey areas) and bond pad openings are etched to allow bonding

18 Reliable Wafer-scale Back-thinning Process Back-thinned SiPM Devices

19 Voxtel SPAD/SiPM Phase II SBIR Efforts Under Review Topic 61: Wafer-Scale Geiger-mode Silicon Photomultiplier Arrays Fabricated Using Domestic CMOS Fab Characterize latest generation of Gm APDs fabricated in Phase I Optimize a low DCR Gm SPAD (SiPM) using Jazz process Assumes a 25-µm pixel pitch Optimized for backside illumination Compatible with large area stitching, but included in program Topic 63a: Digital Silicon Photomultiplier Array Readout Integrated Circuits Characterize digital SPAD ROIC fabricated at Jazz in Phase I Develop a 25 micron pitch ROIC for digital SPADS Designed for hybrid stacked circuit of bump bond integration Design includes: In-pixel AQC In-pixel (sub)pixel enable (Optional) monolithic Gm SPAD, which can be shorted for 3D stacked integration* Sub-block asynchronous TDC Programmable threshold

20 VX-798: High Dynamic Range, Multi-threshold Photon Counting Sensor VX-798 Unit Cell Block Diagram VX-798 Array with Thick, Fully- Depleted Silicon Sensor Model VX-798 Features Calibrated, dual-level threshold detection Programmable 30-bit / (2 x 15-bit) photon counting Low-noise front end optimized for 10 ns and 150 ns bunch timing 130 µm pixel pitch, 48 x 48 array, currently developing a full reticle version of design VOXTEL PROPRIETARY

21 Model VX-803 Features Low-noise pixel design with discriminator and time stamp in each pixel – 300 ns timing resolution at 1 ms gate time Sparse readout of array between bunch train uses pixel “hit” flags for event driven readout 15 µm pixel pitch, 960 x 448 format array ROIC designed for wafer –to- wafer hybridization (Ziptronix) Picture of Model VX-803 VX-803: Time-Resolved HEP Event Detection with Sparse Readout VX-803 (15 µm) pixel Layout VX-803 Pixel Block Diagram VOXTEL PROPRIETARY VX-803 Noise Contributors

22 VX-807: Asynchronous, Time-Resolved, Event-driven Photon Detector Model VX-807 Features Low noise amplifier and discrimination designed for soft x-ray (530 eV) single photon detection Handshaking and address arbitration logic used to handle real-time readout of hit pixels with 40 ns timing resolution Supports >20 MHz photon count rates Totally asynchronous operation 40 um pixel pitch, 492 x 492 full reticle array VX-807 Unit Cell Block Diagram VX-807 Simulated Performance VX-807 Floorplan VOXTEL PROPRIETARY

23 Model VX-803 Large format, low-noise, mega-pixel, hybrid BSI image sensor Fabricated on SOI to achieve full depletion using high resistivity silicon Fabricated on SOI wafers for tolerance to transient singe event effects Capacitive transimpedance amplifier (CTIA) with correlated double sampling (CDS) Radiation hard-by-design techniques on a 0.18 µm CMOS process to increase radiation total ionizing does tolerance SOI CMOS Imager Wafer Photon Transfer Curve VX-803: ad-hard SOI CMOS Star Tracker VX-803: Rad-hard SOI CMOS Star Tracker

24 VX-819: 2D-Array Event-driven Ripple Waveform Sampling Model VX-819 Programmable pulse detection circuit 40 samples in 55 um pixel Programmable sample rate ( 1 ns minimum) Used with curve fitting to achieve 50-ps timing resolution VX-819 Pixel Layout VX-819 Pixel Block Diagram VOXTEL PROPRIETARY

25 In Progress: PS-Waveform Recorder (Phase I SBIR Development) Time resolution versus analog bandwidth for a fixed sampling rate of 40 GSa/s, for input signals of 20 and 50 photo-electrons (Ganat 2008). Time resolution vs sampling jitter for input signals of 100 photo-electrons. The sampling rate is 40 GSa/s, the analog bandwidth is 1.5 GHz (Ganat 2008) Pulse sampling and timing extraction. (Bogdan, 2009) The VX-251 shown in the test platform used to assess functionality. Microscope photo of one end of the VX-805 ROIC, showing the landing spot for the APD die.

26 Multi-channel Time-to-Digital Converter (TDC) and Binary Pulse Processor (BPP) Features for Existing Product 8 CMOS input channels or 64 LVDS input channels Timing resolution < 50ps Measurement range of 13ms (extendable) Count rates of 20 million counts per second (cps) on each channel Large internal memory buffer, with a minimum storage capacity of 65,535 events per channel (262,000 events per channel for 8 channel instrument) Gigabit Ethernet (GbE) to communicate with the host PC. Single 5V power supply for operation Software GUI with statistical analysis features Auto (Cross) Correlation demonstrated with Ƭ min = 3 ns Binary Pulse Processing, Time-over-threshold, and Multi-threshold Processing 64, 128, and 512 versions under development

27 High channel Count, Re-configurable Multi-Purpose Pulse- processing Platform Planned Features Easily reconfigurable pulse-processing platform with multiple daughter boards to meet different application needs Application-specific, pluggable front-end modules – time-stamping (analog and digital inputs), analog to digital conversion, auto and cross-correlation Up to 1000 channels High timing resolution (tens of pico-seconds to sub-ns, depending on the channel count and application) Data transfer rates of up to 400 MB/s Variable measurement times, depending on the application Ability to time-stamp positive and negative edges Ability to measure really short pulses (<1ns) Minimum dead-time between pulses (<3ns) High input pulse count rates (> 250 MHz) User friendly software GUI

28 Thank You

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