LIDAR RECEIVERS FOR AUTOMOTIVE APPLICATIONS...Traffic jam assist Common Level 4 “Brain off” Highway autopilot Must Level 5 “Driver off” Fully autonomous Must y Adoption scenario1

DR. MARC SCHILLGALIES

MAY 07, 2019

LIDAR RECEIVERS FORAUTOMOTIVE APPLICATIONS

Company Overview

Capabilities

− 7 clean room production sites: wafer fab and assembly facilities

− Automotive, medical and aerospace certifications

− Development and production of customized and standard sensors

− Complete sensor value chain from die to system in one company

Short facts

− Founded 1991 in Berlin, Germany

− 970 employees

− 155 Mio€ revenue 2018

− Stock-listed in Germany

Markets & Products

− 3 target markets: industry, automotive, medical

− Sensor products for photonics, pressure, flow and inertial measurement

− Cameras and integrated manufacturing services for imaging sensors

IMS Workshop CMOS Imaging

LIDAR RECEIVERS FOR AUTOMOTIVE APPLICATIONS

LiDAR is a leading technology for fast growing automotive and industrial applications

What makes LiDAR technology unique? How does LiDAR influence automotive and industrial applications?


✓

✓

✓

Au

tom

oti

ve

✓ Safety, comfort and cost reduction of transportation drive development of partly or fully autonomous vehicles

✓ First adaptation of autonomous driving (above Level 3): special vehicles and mobility as a service

✓ Sensor suites combine indispensable LiDAR with multiple sensor technologies for reliable sensing of environment

Ind

ust

rial

✓ Mix of mature and emerging applications

✓ Various industrial applications, including

− Unmanned guided vehicles UGV, drones, robots, general automation

− Security scanners

− Mapping

− Traffic control

− Range finding (point measurement)

Unique advantages over other sensors- Higher spatial resolution than RADAR- Longer range and better night performance than cameras- Much longer range and resolution than ultrasonic sensors

Mature and versatile technology- Proven technology from industrial and aerospace application - Technology can be easily adopted to specific requirements

(range, field of view etc.)- Fusion with other sensors for redundancy and support for artificial

intelligence (automated driving)

Economy of scale- Price degression of LiDAR systems hardware with economy of scale - Over 50 LiDAR companies working on taking LiDAR to automotive level

regarding cost/reliability/performance


Automotive: New Mobility needs LiDAR



Higher level autonomy requires LiDAR Market potential gradually unfolding

Functionality Use of LiDAR

Level 1“Feet off”

Cruise control Rare

Level 2“Hands off”

Lane assist Rare

Level 3“Eyes off”

Traffic jam assist Common

Level 4“Brain off”

Highway autopilot Must

Level 5“Driver off”

Fully autonomous Must

Incr

ease

d L

evel

of

auto

no

my

Adoption scenario1

✓ Global market light vehicles: ~96m in 2018 to ~108m in 2028

✓ 2023 – Market share level 3/4/5: ~4% or 4m cars

✓ 2028 – Market share level 3/4/5: ~26% or 28m cars

0%

20%

40%

60%

80%

100%

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Level 0 Level 1 Level 2 Level 3 Level 4 Level 5

1 Source: UBS 2018.

Distribution of autonomy levels of new passenger cars

Requirements of automotive applications



Which requirements need to be addressed moving to automotive? Why is Si APD the suitable detection technology?

− Low noise bipolar photodiode with internal amplification with very high dynamic

range, suitable for strong ambient light conditions and grade 1 temperatures (-

40°C…125°C)

− Highest absorption efficiency 905nm tuned by thickness of silicon layer

− High bandwidth by high bias for fast transport mechanisms (~ 150V-300V)

− Mature technology with high yields

Cost & Scalability

PerformanceQuality & Reliability

Automotive

− Automotive applications require the optimum balance of

− Sufficient performance over wide temperature range and lighting

conditions

− Cost and volume scalability to support mass market product lines

− Proven reliability within the mission profile

0,0001

0,001

0,01

0,1

1

10

100

1000

10000

0,00001 0,001 0,1 10 1000

Ph

oto

curr

ent

[µA

]

Optical Input [µW]

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-5 5 15 25 35

Pu

lse

amp

litu

de

Time [ns]

Requirements of automotive applications



APD characteristics LiDAR architectures

Point/line scan

Single channel receiver

360° fan scan

Multiple single channel receivers

FOV scan typ. < h140°/v30°

1D/2D receiver array

Ind

ustrial ap

plicatio

ns

Au

tom

otive ap

plicatio

ns

1

10

100

1000

0 100 200

Gai

n

Bias [V]

Typical gain ~ 100

0

10

20

30

40

50

60

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400 900

Spec

tral

res

po

nsi

vity

[A

/W]

Wavelength [nm]

Peak responsivity at 880nm

M=100

Typical BW ~ 400 MHz Dynamic range <1nA … >100mA

30ns pulses, 905nm, RT

Pushing performance limits of avalanche photodetectors



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0 0,2 0,4 0,6 0,8 1 1,2 1,4

Dar

k cu

rren

t (M

=50

) p

er m

m²

pix

el a

rea

[pA

]

Individual pixel area [mm²]

Previous technology

New technology

2 x 32 pixels

Common solid state LiDAR schematic for 1D MEMS

− Detector layout determined by LiDAR system architecture

− With size limitations of 1D MEMS-mirror larger detector arrays are needed

− 2D detector arrays allow for segmented FOV to reduce ambient light influence

− Results APD with 64 pixels of 1,3mm²: 40pA/mm² dark current (avg, RT, M=50)

Dark current density at M=50, 25°C

Pushing performance limits of avalanche photodetectors



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0 0,2 0,4 0,6 0,8 1 1,2 1,4

Dar

k cu

rren

t (M

=50

) p

er m

m²

pix

el a

rea

[pA

]

Individual pixel area [mm²]

Previous technology

New technology

2 x 32 pixels

Dark current (25°C : 125°C) 40pA : 110nA Dark current density at M=50, 25°C

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

0 50 100 150 200 250 300 350

Dar

k cu

rren

t [A

]

Bias [V]

Id 25°C

Id: 125°C

Dark current doubles every 8.8K -> Low RT dark current level needed for HT

operation of APD

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0 50 100 150 200

tr [

ns]

Gain

T=-40°C, LED=0,75µW

T=-40°C, LED=19,5µW

T=0°C, LED=0,75µW

T=0°C, LED=19,5µW

T=25°C, LED=0,75µW

T=25°C, LED=19,5µW

T=85°C, LED=0,75µW

T=85°C, LED=19,5µW

T=125°C, LED=0,75µW

T=125°C, LED=19,5µW

Performance is required from -40°C to 125°C



85%

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115%

-40 -20 0 20 40 60 80 100 120

Res

po

nsi

vity

at

90

5n

m r

elat

ive

to v

alu

e at

25

°C

Temperature [°C]

Spectral responsivity relative to 25°C

0,01

0,1

1

10

100

1000

10 100 1000 10000

Ph

oto

cu

rren

t [µ

W]

optical power [nW]

Iph, -40°C

Iph, 25°c

Iph, 85°C

Iph 125°C

Spectral responsivity relative to 25°C Rise time vs temp (under cw illumination) Linearity vs temp

M=20, cw at 905nm1,3mm² active area, cw at 905nm

Responsivity at 905nm varies only slightly

with temperature

Response time stable with temperature but

requires minimum bias/gain

Linearity in input regime of TIA

stable over temperature

Economy of scale but also higher integration will drive cost down



Price path necessary to reach mass-market

2018 20252021

System price >10,000€

Receiver cost >500€

System price ~400€

Receiver cost ~50€

System price ~200€

Receiver cost ~20€

2.5D photonic hybrid

or

Monolithic digital receiver

Receiver architecture path necessary to reach mass-market

Cost down of APD wafer: Yield improvements



Wafer homogeneity of U(M=100) Wafer homogeneity of U(M=100)

-/+ 1 % change in implantation dose -> -/+ 9,2 % change in U(M=100)

-/+ 10 % change in epi thickness -> -/+ 4,5 % change in U(M=100)

-/+ 30 % change in epi doping -> -15,5 %/+6,5 % change in U(M=100)

220V 210V

For large APD arrays wafer homogeneity translates into yield

Improvements achieved with tighter control on implantation and material parameters

Cost down of APD wafer: Yield improvements



Photoemission microscopy of APD (M=1000, avalanche luminescence below 1700nm)

Responsivity scan of APD (M=100, 10µm spot, 5µm steps) Burst noise (phantom signal)

Responsivity at 905nm shows micro-

inhomogeneities due to gain variation

20 µm

At high multiplication high gain regions

break down early (high avalanche

luminescence)

Local break down causes short signal

bursts that can be misinterpreted as

reflections from target

Cost-effective scalable packaging solution



− In many cases IR-optimized detector and readout IC have different

technologies

− System in a package is well established in electronics, necessity for optical

window reduces number of available or economically attractive technologies

− Example: film assisted molding of detector with glued glass and ROIC

− Close proximity of ROIC requires thermal management

Silicon

GlassMold

Automotive industry is known for quality requirements



AEC-Q of product

− Defined standard of tests with limited sample qty

− 100% pass = qualified product

− No possibility to learn from failures

Certified production

− Harmonized automotive quality management system:

IATF 16949:2016

− Applied throughout supply chain, development & operations

Functional Safety

− Build in redundancy

− Design system capability from start

− Determine failure risks

− Often focus on system level but component level functional safety helps

AEC-QSeries

AEC-Q100IC Chips

AEC-Q102Optoelectronics

AEC-Q101Components

AEC-Q104SIP

AEC-Q200Passives

Robustness Validation

− Requirements become harder – higher temperature, longer lifetime, lower failure rates

− Find out limits of product

− Evaluate robustness margin with help of mission profile

HTRB test shows that semiconductor life time is very good, but…



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0 200 400 600 800 1000 1200

Sum

dar

k cu

rren

t (1

00

dev

ices

3 p

ixel

eac

h)

[µ

A]

Time [h]

300 APDs in series, operated at 125°C,150 V

AEC-Q-Test HTRB

− Test of 100 devices with 3 pixels each

− 125°C, 150V bias, no humidity, no light

− DUT are connected in series, dark current is recorded

− Semiconductor shows only very little aging

Dark current

+6,9% / 1000h

..H3TRB test reveals automotive capability of packaging design and materials



Corrosion causes leakage paths

Without corrosionInfluence of humidity: AEC-Q-Test H3TRB (Bias 100 V, 85 °C, 85 % r.h.)

Summary



LiDAR has enormous market potential, driven by the mega trend of autonomous driving ✓

Silicon APD technology is matching performance, cost and quality requirements in automotive✓

It is possible scaling APDs in size and extending specification to grade 1 temperature range ✓

Receiver cost down achievable by economy of scale, higher array yield and integration densities ✓

Choice of proper packaging technology determines automotive reliability✓

First Sensor AGwww.first-sensor.com

LiDAR receivers for automotive applications

THANK YOU.

May 7, 2019

Dr. Marc Schillgalies, Dr. Frank Kudella, Philipp Moock, Gerd Lange, Sven Stissel, Holger Arndt, Stephan Dobritz, Lutz Mattheier

Documents

LIDAR RECEIVERS FOR AUTOMOTIVE APPLICATIONS...Traffic jam assist Common Level 4 “Brain off” Highway autopilot Must Level 5 “Driver off” Fully autonomous Must y Adoption scenario1