Workpackage N° 4 1 Nanospad Review meeting Brussels, May 6 2008 Full Title: Single Photon Avalanche...

Nanospad Review meeting Brussels, May 6 2008Workpackage N° 4 1

Full Title: Single Photon Avalanche Diode (SPAD) per la lettura di Fibre Scintillanti

Bando ASI per lo Sviluppo Tecnologico Coordinating person: Piera Maccagnani Partecipants: CNR-IMM, INAF-IASF Bologna, Poli-MI, Micro Photon Devices, Finanziamento richiesto: 300 k€ per 24 mesi Stato: ammesso al finanziamento Data di inizio: ????

FIBER-SPAD PROJECT

Attività: • realizzare rivelatori SPAD a grande area attiva (diametro di almeno 500m) da

interfacciare con fibre scintillanti. • progetto e realizzazione dell’elettronica non standard di acquisizione ed

elaborazione del segnale. • test delle prestazioni del sistema complessivo con sorgenti e fasci di particelle.

Obiettivo: realizzazione di un rivelatore per raggi gamma basato su fibre scintillanti con lettura mediante Single Photon Avalanche Diode (SPAD).


Full Title: Protein microarray for enhanced diagnostics at low cost by integration of new technological developments

6FP – STREP Thematic Priority: IST-NMP-2 Bio-sensors for Diagnostic and Healthcare Coordinating person: Prof. Sergio Cova (MPD) Partecipants: Poli-MI, CNR-IMM e ICRM, CNRS, Univ. College Cork, Paul-Erlich

Institut, Univ. Claude Bernard Lyon1 Finanziamento: 310 k€ per 30 mesi, 60 man months Durata: 1/12/2005 – 31/5/2009

NanoSPAD PROJECT

Obiettivo: sviluppare uno strumento compatto per una diagnosi rapida e a basso costo delle allergie, basato su un micro-array biologico e su una matrice di rivelatori SPAD

Attività IMM-BO: sviluppare una matrice di rivelatori SPAD da interfacciare al micro-array biologico (WP4)


Final objective: To develop a To develop a compact compact apparatusapparatus that can efficiently that can efficiently detect and measure arraysdetect and measure arrays of of proteins labeled with proteins labeled with luminescent probes.luminescent probes.The apparatus will employ a The apparatus will employ a matrix of single-photon matrix of single-photon detectorsdetectors (typically 48 (typically 48 detectors).detectors).Each element of the matrix is Each element of the matrix is intended to measure the intended to measure the emission intensity from one of emission intensity from one of the micro-spots of the protein the micro-spots of the protein microarray.microarray.

NanoSPAD PROJECT


Basic concept: use of an Array detector

Target application:

“in-vitro” allergy diagnosis with

chemiluminescent protein microarray

Optical implementation:

Each spot of the microarray is conjugated to a SPAD pixel through a 1:1 imaging optics


WP4 - Development of monolithic arrays of SPADsDevelopment of monolithic arrays of SPADs

Matrix of SPAD detectors with wide pixel area 2x3mm2 matrices with 48 SPAD elements, 240 m pitch matrix pixels with active area diameter of 50m matrix geometry conjugated to that of the allergen microarray good performances obtained for single pixel-SPAD good SPAD performance uniformity inside the matrix

4 interleaved sectors including 12 pixels with common anode

sector 1

sector 2

sector 3

sector 4


Detector noise sources:

• Thermal Carrier Generation (Dark Counting Rate, DCR)

• Carrier Trapping and Delayed Release (Afterpulsing effect)

Reducing the Detector NoiseReducing the Detector Noise

For achieving low noise:

Good quality substrates

Clean processing

Efficient GETTERING

Reduced electric field


Improved Technological SPAD process

isolfield

active

xx

metal

• Implant to realize the p+ doped region• Process to oxidize the SPAD active area• Gettering processes• Different cleaning during technological process


Effect of Effect of CLEANINGCLEANING processes processesMain characteristic processes:• active area oxidation• doping of p+ regions• defects gettering• process cleaning

• Uniform reduction of DCR @Tamb (21°C)

• Best DC reduced of 50%

• Plasma cleaning introduces defects in the SPAD active area.


Effect of Effect of IMPLANTIMPLANT process for p process for p++ regions regions

• Uniform reduction of DCR @Tamb (21°C) 5 times

• Implanting BF2 we introduce defects in the SPAD active area. Probably due to Mo contamination.

Main characteristic processes:• active area oxidation• doping of p+ regions• defects gettering• process cleaning


Effect of Effect of OXIDATIONOXIDATION process process

• Same trend for the 2 oxides

• Same DC low level @Tamb

• LTO shows lower % of “good” devices

Main characteristic processes:• active area oxidation• doping of p+ regions • defects gettering• process cleaning


Effect of Effect of GETTERINGGETTERING process process

• Same trend and behaviour of DC @Tamb

• NO CLEAR effect of the gettering process

Main characteristic processes:• active area oxidation• doping of p+ regions• defects gettering• process cleaning


OLDOLD vs vs NEWNEW Process Flow Process Flow

• Higher % of devices with DCR<1kc/s @21°C:44% in NEW Run vs 10% in the OLD Run

• NEW Run Best devices with 300-500 counts/s vs 700-1000c/s from OLD Run

Selected processes:• Thermal oxidation• Boron doping of p+ regions • Long gettering (5h)• Wet cleaning


OLDOLD vs vs NEWNEW Process: large area SPAD Process: large area SPAD

• lower DCR confirmed also for 100m SPAD

• Higher % of devices with DCR<5kc/s @21°C:26% in NEW Run vs 7% for OLD Run

• NEW Run Best devices with a thousand counts/s vs thousands counts/s in the OLD Run


Wafer distribution map

• Full wafer characterization:300 SPAD - 50m600 SPAD - 100m

• Confirmed good fabrication yield for 50 and 100m single SPAD

• Good uniformity in VBD values distribution: VBD=36.1V ± 0.5V

• Low detector noise:< 1kc/s for 45% of 50m SPAD< 10kc/s for 70% of 50m and 40% of 100m SPAD< 100kc/s up to 200m SPAD

Pass SPAD8 S8-3 TEST AVGVBD %y

37.1936.7036.2135.7235.2334.7434.25

detection limit is not imposed by DCR of the detector NO COOLING required


6x8 SPAD matrix detector6x8 SPAD matrix detector

• 50 µm pixel diameter

• 240 µm pitch

• 4 interleaved sectors including 12 pixels with common anode

sector 1

sector 2

sector 3

sector 4


Matrix Breakdown Voltage distributionMatrix Breakdown Voltage distribution

All 48 pixels commonly working no blind zone in the matrix

• Good process control:new run: 36.2V ± 23mVold run: 37.9V ± 34mV

• Good uniformity obtained in: Photon detection efficiency Series resistance


Matrix Dark Counting Rate (DCR)Matrix Dark Counting Rate (DCR)

Percentage of individual SPAD elements (horizontal scale) found within a given limit of the individual dark counting rate (vertical scale) measured for old and new SPAD matrix.

Reduced DCR level confirmed also for the 50m SPAD in the matrix:

42% pixels with DCR<1 kc/s 90% pixels with DCR< 10kc/s

NO COOLING required for matrix operation in NanoSPAD project


Dark Counting Rate vs TemperatureDark Counting Rate vs Temperature

Dark count: combined effect of band-to-band tunneling (dotted line) and SRH generation (dashed line). The two contributions equals ~ -10°C

• reduced band-to-band contribution due to engineered profile for electric field

→ better DC reduction lowering temperature

• very low DCR even @ 20°C

due to cleanup and gettering

processes in the active region

• Afterpulsing

No AP @ 20°C with tH=250ns

AP=1% @ 20°C with tH=70ns

AP=1.5% @ -15°C tH=70ns


Matrix Photon Detection EfficiencyMatrix Photon Detection Efficiency

4% PDE spreading @530nm

inside matrix (48 pixels)

• lower PDE value:

@530nm 48-52% old

vs 44-48% new

Reduced thickness for the coating

SiO2 layer

New run:• PDE max = 48% @530nm• PDE > 30% over visible range


Matrix PDE and Luminol SpectrumMatrix PDE and Luminol Spectrum

Luminol emission peak= 445nm

SPAD PDE@445nm = 35÷38%

quite good value

Spectrum of chemiluminescence emitted following the catalysis of the reaction by the label.


WP4: Achievements – problems – further actions

Achievements: Good performance SPAD matrices with 48 elements obtained in shorter time than

planned (24 months instead of 30 months)

Development of a NEW Process Flow for advanced SPAD devices: Improved performances obtained for single SPAD devices with 50m diameter

and for monolithic SPAD matrix with 48 detectors: low operating voltage: ~ 36V very uniform matrix breakdown voltage uniform PDE PDE >30% in the spectral range 500 – 700nm very low and uniform dark counting rate: ≤1kc/s for 45% matrix pixels

no cooling required for matrix operation low afterpulsing effect: ~ 1% @ 20°C with tH=70ns reduced band-to-band tunneling due to low electric field profile

better DC reduction at low temperature operation

Workpackage N° 4 1 Nanospad Review meeting Brussels, May 6 2008 Full Title: Single Photon Avalanche...

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