a large scale HV-CMOS pixel sensor

(1)

Performance of MuPix8

a large scale HV-CMOS pixel sensor

Heiko Augustin on behalf of the Mu3e Pixel team

Physikalisches Institut Heidelberg

PIXEL 2018 Taipei 13. December 2018

HighRR

(2)

Motivation - The Mu3e Experiment

Searching for the charged Lepton Flavor Violating decayµ⁺→e⁺e⁻e⁺

Target Inner pixel layers

Outer pixel layers Recurl pixel layers

Scintillator tiles μ Beam

sensitivity goal of one in 10¹⁶decays, requires high muon rates of 10⁹s⁻¹ reconstruction of electron trajectories in a 1 T solenoidal magnetic field multiple coulomb scattering dominated (pe<53 MeV/c)

(3)

Motivation - The Mu3e Experiment

Searching for the charged Lepton Flavor Violating decayµ⁺→e⁺e⁻e⁺

Pixel Sensor Requirements

Pixel Size Time Resolution Material Budget Efficiency 80×80µm² <20ns <1hX₀ / layer ∼100%

sensitivity goal of one in 10¹⁶decays, requires high muon rates of 10⁹s⁻¹ reconstruction of electron trajectories in a 1 T solenoidal magnetic field multiple coulomb scattering dominated (pe<53 MeV/c)

(4)

High Voltage - Monolithic Active Pixel Sensor (HV-MAPS)

P-substrate N-well

Particle E field

I.Peric, P. Fischer et al., NIM A 582 (2007) 87 low ohmic substrate

(20Ωcm - 200Ωcm) high voltage (−120 V) 180nm HV-CMOS process

large depleted n-well diode charge collection via drift no additional readout chip thinned to 50 µm

(5)

The MuPix Concept

PixelsPeriphery

State

MuPix7 as an example active pixel matrix digital pixel cell in periphery

state machine (VCO, PLL, etc., not shown)

(6)

The MuPix Concept

PixelsPeriphery

State

Sensor

Charge sensitive amp

Source follower

Thepixel has

reverse biased diode charge sensitive amplifier

signal transmitter

(7)

The MuPix Concept

PixelsPeriphery

State

Transmission line

signal transmission: point to point connection pixel to periphery

(8)

The MuPix Concept

PixelsPeriphery

State

tune DAC amp baseline

global threshold

peripheral cell: digitisation individual pixel tuning (thr) This separation protects the analog cell from digital crosstalk.

(9)

Introduction MuPix8 Results Summary & Outlook

The MuPix Concept

PixelsPeriphery

State

detecting a signal signal generation

amplification transmission digitisation

timestamp sampling column-drain readout of time and address

serialisation and stream out at 1.25 Gbit s⁻¹

(10)

The MuPix Concept

PixelsPeriphery

State

detecting a signal signal generation amplification

transmission digitisation

(11)

The MuPix Concept

PixelsPeriphery

State

detecting a signal signal generation amplification transmission

digitisation

(12)

The MuPix Concept

PixelsPeriphery

State

detecting a signal signal generation amplification transmission digitisation

(13)

The MuPix Concept

PixelsPeriphery

State

timestamp sampling

column-drain readout of time and address

(14)

The MuPix Concept

PixelsPeriphery

State

Time- stamp

timestamp sampling

column-drain readout of time and address

(15)

The MuPix Concept

PixelsPeriphery

State

Time- stamp Data

(16)

The MuPix Concept

PixelsPeriphery

State

Serialiser

Data Time- stamp

(17)

The MuPix7 prototype - Results

column direction [um]

0 20 40 60 80 100 120 140 160 180 200

row direction [um]

0 20 40 60 80 100 120 140 160 0.75

0.8 0.85 0.9 0.95 1

Efficiency Efficiency

0.88 0.9 0.92 0.94 0.96 0.98

Efficiency0.98 0.96 0.94 0.92 0.9

80×103 µm² pixel size 3.3×3.3 mm²

20Ωcm substrate full system on-chip very well understood

(18)

The MuPix7 prototype - Results

600

− −500 −400 −300 −200 −100 0

Entries [1/run]

102 103 104

Time diﬀrence between hit and scintillator time [ns]

σ= 14.3 ns

99.5% efficiency

with 14.3 ns time resolution

@ 300 mW cm⁻²

time walk observed & signal line crosstalk

(19)

The MuPix7 prototype - Results

0 20 40 60 80 100 120

0 50 100 150 200 250

0 10 20 30 40 50 60 70 80 90

ToTtime Trigger Difference versus ToT

Latency [2,5ns]

ToT [10ns]

99.5% efficiency

with 14.3 ns time resolution

@ 300 mW cm⁻²

time walk observed & signal line crosstalk

(20)

Scale it up!

(21)

The first large scale prototype - MuPix8

Group Ivan Peric @KIT

AMS aH18 process (180 nm) 80×81 µm² pixel size 16×10 mm² active area 128×200 pixels

(22)

MuPix8 Design Features

submatrix A

submatrix B

submatrix

C

digital periphery pixel matrix

bias blocks & pads 10.8 mm

19.5mm

128 columns

48 48 32

200 rows

2×1 cm² chip size

→ full column length radiation hard design

time walk correction possible increased signal charge

(20→80−200Ωcm substrate) thinned to 62.5 µm + 100 µm bandgap reference, voltage DACs, ...

(23)

MuPix8 Architecture

Pixel Periphery State Machine

readout state machine

VCO

&

PLL

8b/10b

encoder serializer LVDS ...

other pixels

LVDSLVDS

MUX LVDS

sensor CSA

comparator 1&2

tune DAC

threshold baseline

test-pulse injection

readout

x3

integrate charge

ampliﬁcation

line driver per pixel digital output

threshold adjustment

3 sub-matrices with individual data output additional merged/mirrored data output

→ 4 differential links @ 1.25 Gbit/s

(24)

MuPix8 - Signal Transmission

Bias Voltage

Bias Voltage Bias Voltage

Comparator CSA

Pixel

Periphery Res

very dense routing:

2 metal layers,

200 signal lines per column sub-matrix A: source follower

→ prone to crosstalk

sub-matrix B&C: current driven

→ aiming for crosstalk reduction

(25)

MuPix8 - Pixel Peripheral Cell

∆t

Amplitude

short ToT Time long ToT

Threshold

Time walk

2 comparators

3 time walk correction approaches 5 tune bits + pixel switch

10 timestamp bits 6 bit ToT

(26)

MuPix8 - Pixel Peripheral Cell

Comp Thr1 Signal

Thr2 Comp Signal

Voltage

Time Threshold1

Threshold2 Signal

Hold TimeStamp

Store Timestamp

& Hit Flag

2-threshold On-Chip suppression

2 comparators

(27)

MuPix8 - Pixel Peripheral Cell

Voltage

Time Dynamic Threshold

ToT Threshold

Baseline

Thr Comp Signal

Dynamic Threshold

Start Ramp

& Store Timestamp

Dyn Thr Comp Signal

Store ToT Timestamp

& Hit Flag

voltage ramp Off-Chip correction

2 comparators

(28)

Setup

(29)

Characterisation Setup

motherboard with insertable PCB versatile tool

integration for MuPix-like sensors:

MuPix8, AtlasPix, MuPix9, MuPix7 lab characterisation

(30)

MuPix Telescope

4-8 layers of sensors one sensor as DUT

integration test for the Mu3e readout system

(31)

MuPix Telescope

extensive testbeam campaigns: DESY, PSI and MAMI online efficiency

fast analysis framework

(32)

MuPix Telescope

All-AtlasPix telescope proof of principle

performed exemplary threshold scans

(33)

Results

(34)

Commissioning

submatrix A

submatrix B

submatrix

C

digital periphery pixel matrix

bias blocks & pads 10.8 mm

19.5mm

128 columns

48 48 32

200 rows

early breakdown @−60 V (120V design)

powering issue in the digital part

→ tuning possible but not effective pixel switch is working

configuring with 6 Mbit s⁻¹ (100 ms per chip)

more than 10 MHits/s per matrix

(35)

Efficiency

(36)

Matrix A - Efficiency & Noise

efficiency

0.4 0.5 0.6 0.7 0.8 0.9 1

col / pixel

0 10 20 30 40

row / pixel

0 20 40 60 80 100 120 140 160 180

noise rate per pixel / Hz

−1

10 1 10 102

103

104

not matched col / pixel

0 10 20 30 40

not matched row / pixel

0 20 40 60 80 100 120 140 160 180

(37)

Matrix A - Efficiency & Noise

threshold / mV 40 60 80 100 120 140 160 180

efficiency

0.8 0.85 0.9 0.95

1 efficiency

noise

noiserate per pixel / Hz

1

10−

1 10

50 mV threshold = 650e⁻ highly efficient(>99.9%), low noise plateau further increase by masking hot pixels increase with higher HV and resistivity

(38)

Matrix A - Efficiency & Noise

threshold / mV 40 60 80 100 120 140 160 180

efficiency

0.8 0.85 0.9 0.95

1 efficiency

noise

noiserate per pixel / Hz

1

10−

1 10

(39)

Matrix A - Efficiency & Noise

threshold / mV

60 80 100 120 140

hit efficiency

0 0.2 0.4 0.6 0.8 1 1.2

50 V 15 V 05 V

(40)

Matrix A - Efficiency & Noise

threshold / mV

60 80 100 120 140

hit efficiency

0 0.2 0.4 0.6 0.8 1 1.2

m 50V µ cm 100 Ω 200

m 50V µ cm 725 Ω 80

(41)

Matrix A - Sub-Pixel Studies

efficiency

0.93 0.94 0.95 0.96 0.97 0.98 0.99 1

µm x / 0 20 40 60 80 100 120 140 160

mµ y /

0 20 40 60 80 100 120 140 160

HV = -50V, optimal settings utilising the EUDET-telescope at DESY position resolution ≈6 µm

folded map to 2×2 pixel

→ inefficiency at the pixel edges

(42)

Matrix A - Sub-Pixel Studies

efficiency

0.93 0.94 0.95 0.96 0.97 0.98 0.99 1

µm x / 0 20 40 60 80 100 120 140 160

mµ y /

0 20 40 60 80 100 120 140 160

HV = -15V, high threshold utilising the EUDET-telescope at DESY position resolution ≈6 µm

folded map to 2×2 pixel

(43)

Matrix A - Sub-Pixel Studies - Clustering

0 2 4 6 8 10 12 14 16

cluster size

−6

10

−5

10

−4

10

−3

10

−2

10

−1

10 1

Entries

15 V: mean 1.176 50 V: mean 1.186

Cluster sizes very low average cluster size

charge sharing at edges and corners

(44)

Matrix A - Sub-Pixel Studies - Clustering

matched

0 10 20 30 40 50

µm x / 0 20 40 60 80 100 120 140 160

mµ y /

0 20 40 60 80 100 120 140 160

Single Hits very low average cluster size

charge sharing at edges and corners

(45)

Matrix A - Sub-Pixel Studies - Clustering

matched

0 2 4 6 8 10 12 14

µm x / 0 20 40 60 80 100 120 140 160

mµ y /

0 20 40 60 80 100 120 140 160

Double Cluster very low average cluster size

(46)

Matrix A - Sub-Pixel Studies - Clustering

matched

0 0.5 1 1.5 2 2.5 3 3.5 4

µm x / 0 20 40 60 80 100 120 140 160

mµ y /

0 20 40 60 80 100 120 140 160

Triple Cluster very low average cluster size

(47)

Matrix A - Sub-Pixel Studies - Clustering

matched

0 0.5 1 1.5 2 2.5 3

µm x / 0 20 40 60 80 100 120 140 160

mµ y /

0 20 40 60 80 100 120 140 160

Quadrupel Cluster very low average cluster size

(48)

Time Resolution

(49)

Matrix A - Timing Studies

/ ndf

χ2 1.96e+05 / 22

Constant 7.056e+05 ± 4.765e+02 Mean −0.02349 ± 0.00972 Sigma 16.8 ± 0.0

time difference / ns

−300 −200 −100 0 100 200 300 400

entries

0 0.1 0.2 0.3 0.4 0.5 0.6 106

× χ² / ndf 1.379e+05 / 22

Constant 6.005e+05 ± 4.015e+02 Mean 18.65 ± 0.01 Sigma 20.02 ± 0.01

Sensor time resolution: ≈20 ns

lab measurement with Sr90 and scintillating tile

time walk observed pixel position delay (routing and power distribution)

(50)

Matrix A - Timing Studies

Time-Walk corrected Hit TS - Trigger TS [8ns]

−6 −4 −2 0 2 4

entries

0 10 20 30 40 50 60

/ ndf

χ2 6.506 / 5

scale 58.17 ± 7.13 mean [bins] −1.811 ± 0.091

[bins]

σ 0.7552 ± 0.0679

BG slope 0.003091 ± 0.000832

0.544 [ns]

± = 6.042 σ

Single pixel(0/1) time resolution

(51)

Matrix A - Timing Studies

entries

10 20 30 40 50 103

×

Hit TS - Trigger TS [8ns]

−10 −5 0 5 10

ToT [64ns]

10 15 20 25 30 35 40

Time walk: raw data

(52)

Matrix A - Timing Studies

Peak position [bins]

−2

−1 0 1 2 3 4 5

col block

0 1 2 3 4 5 6 7

row block

0 5 10 15 20

Pixel position delay

(53)

Matrix A - Timing Studies

entries

10 20 30 40 50 60 103

×

Delay corrected Hit TS - Trigger TS [8ns]

−10 −5 0 5 10

ToT [64ns]

10 15 20 25 30 35 40

Time walk: delay corrected

(54)

Matrix A - Timing Studies

entries

10 20 30 40 50 60 103

×

−10 −5 0 5 10

ToT [64ns]

10 15 20 25 30 35 40

Delay + Time walk correction

(55)

Matrix A - Timing Studies

2Thr ThLow 520mV 2Thr ThLow 525mV 2Thr ThLow 530mV 2Thr ThLow 535mV ToT

Time Resolution [ns]

4 6 8 10 12 14 16 18 20

complete chip row ≤ 20

uncorrected uncorrected

delay corrected delay corrected delay + tw corrected delay + tw corrected

Time resolution: σ = 6.5 ns

(56)

Crosstalk

(57)

Matrix A - Signal Line Crosstalk

capacitive coupling row dependence

→ increased readout load

→ signal reduction

→ degrade rising edge

(58)

Matrix A - Signal Line Crosstalk

charge sharing

charge sharing / crosstalk

crosstalk

(59)

Matrix A - Signal Line Crosstalk

row / pixel

20 40 60 80 100 120 140 160 180

triple crosstalk

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

/ ndf

χ2 2933 / 172

threshold 72.69 ± 0.109 offset 0.0002191 ± 1.914e−05 slope 0.002792 ± 8.422e−06

/ ndf

χ2 2933 / 172

(60)

Matrix A - Signal Line Crosstalk

threshold / mV 40 60 80 100 120 140 160 180

crosstalk / %

0 2 4 6 8 10

Threshold dependence

(61)

Matrix A - Signal Line Crosstalk

threshold / mV 40 60 80 100 120 140 160 180

clustersize / pixel

1.03 1.04 1.05 1.06 1.07 1.08

Crosstalk removed

(62)

Matrix A - Signal Line Crosstalk

threshold / mV 40 60 80 100 120 140 160 180

efficiency

0.8 0.85 0.9 0.95 1

= 235.75 µ Row 0 :

= 228.89 µ Row 100 :

= 221.92 µ Row 199 :

Signal reduction

(63)

Matrix B - current driver

(64)

Matrix B - Efficiency

efficiency

0.4 0.5 0.6 0.7 0.8 0.9 1

50 60 70 80 90

row / pixel

0 20 40 60 80 100 120 140 160 180

recent testbeam measurement preliminary result

highly efficient >99%

further analysis ongoing

(65)

Matrix B - Time Resolution

−20 −15 −10 −5 0 5 10 15 20

entries

0 0.2 0.4 0.6 0.8 1 1.2 1.4 106

×

/ ndf

χ2 2.7e+04 / 7

scale 1.367e+06 ± 7.022e+02 mean [bins] 0.4557 ± 0.0008

[bins]

σ 1.925 ± 0.001

BG slope 42.51 ± 0.30

0.009 [ns]

± = 15.401 σ

investigation with coincidence setup delay compensation + time walk correction

→ time resolution: σ <15 ns

(66)

Matrix B - Time Resolution

ThLow

520 mV 530 mV 540 mV 550 mV 560 mV

Time Resolution [ns]

5 10 15 20 25 30 35 40

uncorrected delay corrected delay + tw corrected

investigation with coincidence setup delay compensation + time walk correction

→ time resolution: σ <15 ns

(67)

Matrix B - Crosstalk

row / pixel

0 20 40 60 80 100 120 140 160 180

triple crosstalk

−0.02 0 0.02 0.04 0.06 0.08 0.1

no crosstalk observed!

current driver allows for dense rounting

(68)

Summary & Outlook

(69)

Summary

Pixel Sensor Performance

Matrix A Matrix B AtlasPix

Efficiency >99.9% >99% >99.9%

Time res 6.5 ns 15 ns 10 ns

Crosstalk yes no no

Power 200 mW cm⁻² 210 mW cm⁻² 300 mW cm⁻² exceptional performance →scaling successful

obvious improvements at hand: breakdown, powering, ...

current driver scheme can be further improved

(70)

Outlook

4.5mm

3.5mm

MuPix9

MuPix9: shunt, serial powering, mu3e slowcontrol interface ...

AMS aH18: long delivery times qualification of new foundry:

TSI Semiconductors (H18) resubmitted MuPix7 to TSI testbeam analysis ongoing

submission of fullscale sensor in 2019

(71)

Acknowledgments

Many important test beam campaigns have been performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF).

We would like to thank the PSI for providing high rate test beams under excellent conditions.

We thank the Institut für Kernphysik at the JGU Mainz for giving us the opportunity to take data at MAMI.

(72)

Thank you

(73)

Back-up

(74)

trigger_ts_diff

Entries 399254

Mean −0.6394

RMS 8.511

/ ndf

χ2 213.9 / 3

p0 4253 ± 62.7 p1 −4.175 ± 0.016 p2 1.136 ± 0.020 p3 1216 ± 31.8

−15 −10 −5 0 5 10 15

1000 1500 2000 2500 3000 3500 4000 4500 5000

5500 trigger_ts_diff

Entries 399254

Mean −0.6394

RMS 8.511

/ ndf

χ2 213.9 / 3

p0 4253 ± 62.7 p1 −4.175 ± 0.016 p2 1.136 ± 0.020 p3 1216 ± 31.8

Trigger TimeStamp Difference Distribution

Time resolution:

MuPix7_TSI

(75)

Sensor hit rate [kHz]

1 10 10² 10³ 10⁴

Average readout load

−4

10

−3

10

−2

10

−1

10 1 10

Sensor 0 Sensor 1 Sensor 2 Sensor 3 Sensor 4 Sensor 5 Sensor 6 Sensor 7

Rate test

(76)

col / pixel

50 60 70 80 90

row / pixel

0 20 40 60 80 100 120 140 160

180 efficiency

0.95 0.955 0.96 0.965 0.97 0.975 0.98 0.985 0.99 0.995 1

(77)

MuPix8 MuPixX

Bias Voltage

Bias Voltage Bias Voltage

Comparator CSA

Pixel

Periphery Res

(78)

Pixel Matrix

Digital Cells Signal lines

(79)

103 µm

80 µm

(80)

row / pixel

20 40 60 80 100 120 140 160 180

double crosstalk

0 0.1 0.2 0.3 0.4

0.5χ² / ndf 7609 / 177 scale 0.06542 ± 0.0002717

µ 95.04 ± 0.2851

σ 22.57 ± 0.218 / ndf

χ2 7609 / 177

scale 0.06542 ± 0.0002717

µ 95.04 ± 0.2851

σ 22.57 ± 0.218

row / pixel

20 40 60 80 100 120 140 160 180

triple crosstalk

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

0.4χ² / ndf 2933 / 172

/ ndf

χ2 2933 / 172

(81)

threshold / mV 40 60 80 100 120 140 160 180

clustersize / pixel

1.02 1.04 1.06 1.08 1.1 1.12 1.14 1.16 1.18 1.2 1.22

w/ crosstalk

(82)

threshold / mV 40 60 80 100 120 140 160 180

clustersize / pixel

1.03 1.04 1.05 1.06 1.07 1.08

w/o crosstalk