SiPM and SPAD Sensors for LiDAR and 4D Imaging

Jack Qian PhD

The 29th MEMS Seminar: LiDAR Technology and Application

September 2020

ON Semiconductor Today

• Headquarters: Phoenix, AZ

• Employees: ~35,000 globally

• Revenue: ~$5.5Bn(1)

Spin-Off

1999

IPO

2000

(1) Based upon 2019 results

2

ON Semiconductor Today

• Headquarters: Phoenix, AZ

• Employees: ~35,000 globally

• Revenue: ~$5.5Bn(1)

(1) Based upon 2019 results

Power SolutionsGroup

Semiconductor products that perform multiple application functions, including power

switching, signal conditioning, circuit protection, signal

amplification and voltage reference

Intelligent Sensing Group

CMOS image sensors, image signal processors, radar, and

LiDAR, for automotive, industrial, medical, and aerospace / defense

markets

Advanced SolutionsGroup

Analog, mixed-signal and advanced logic ASIC and ASSP solutions for a broad base of

applications in the automotive, industrial, communications,

medical and aerospace / defense markets

3

SensL Division (SLD) of Intelligent Sensing Group (ISG)

SensL acquired by ON Semiconductor May 2018

Independent division within ISG focused on LiDAR solutions

Division engineering remains in Cork Ireland

Leveraging resources of all 35,000 ON employees

ISG HQ

Santa Clara, CA USA

ON Semiconductor

Phoenix, AZ HQ

Keith Jackson CEO

Advanced Solutions

Group (ASG)

Power Solutions

Group (PSG)

Intelligent Sensing

Group (ISG)

Commercial Solutions

Division (CSD)

Industrial Solutions

Division (ISD)

Automotive Sensing

Division (ASD)SensL Division (SLD)

Sales

Finance

Mfg/Ops

SensL Division Reporting Structure

Corporate Mktg

Corporate R&D

World HQ

Phoenix, AZ USA

SensL Division HQ

Cork, Ireland

4

Intelligent Sensing Group

Automotive Machine Vision Edge AIViewing, ADAS, AD Robotics, ITS, Prem. Security Future Retail, Smart Home

57% of rev 25% of rev 18% of rev

All sensor modalities

Top to bottom platform

Market share leader

Widest GS portfolio

Expanding applications

#1 in Machine Vision

Widest GS portfolio

Driven by AI

Fast growing

5

LiDAR Depth Info: Key for Autonomous Perception

6

Robotic Transport (Delivery, Industrial, Agriculture)

L3 – L5 Autonomous Vehicles(Early R&D Trials, Mass Market OEM Vehicles, Robotic Taxis)

Source: Yole

ON Semiconductor offers the complete suite of

sensors for autonomous perception:

Imaging Radar LiDAR

Source: Yole

Direct ToF LiDAR – Simple Concept

... Made challenging by the real world requirements

+ Many suppliers emerging for all use cases

7

LiDAR Functions Roadmap

• Illumination in NIR spectrum

Transmit

• Return photon detection

Receive

• Scanning/Scene Illumination

Beam Steering

• TX and RX focusOptics

• Signal processing and point cloud

Readout

• Power managementPower and

System

Typical LiDAR System Block Diagram

Six Major Hardware Functions

block on a LiDAR System:

Key strategic focus for ON Semiconductor is to offer system, sensor, readout and laser driver solutions for all NIR LiDAR architectures

Power

Management

SiPM/SPAD

Amplification &

Discrimination

Laser

Diode/VCSEL

Transmit

Beam Steering

Receive

Beam Steering

Optomechanical subsystem

Laser Driver

Timing,

Histogramming

& Point Cloud

Actuator

Driver

ON Semi &

CustomerON Semi

ON Semi

ON Semi

ON Semi

8

LiDAR Scene Illumination

• Mechanical

• Galvo

• Raster Scan

Flash

Rotating

Beam-Steering

• MEMS | LC | OPA

• Scan on transmit & receive

• Scan on transmit only

• System Alignment

• Auto Qualification

• Popular today

• Staring transmit & receive

• VCSEL array + SPAD array

• Flash with no scanning

• Flash “electronic scanning”

Scanning Methods Challenges/Benefits

• Angle of View tied to sensor

• “Solid state” / solid state

• Efficient for long-range

• Highest angular resolution

• True solid state

• Shorter range

9

Types of Photodetectors for LiDAR

10

PIN DiodesAvalanche

Photodiodes & APD Arrays

Single Photon Avalanche Diodes &

SPAD Arrays

SiliconPhotomultipliers &

SiPM Arrays

Hamamatsu Hamamatsu

✔ Low Voltage

✔ Good Uniformity

✖ No Gain

!! Linear Mode

⇓ Market Adoption

✖ High Voltage

✖ Poor Uniformity

✔ Moderate Gain (102)

!! Linear Mode

⇘Market Adoption

✔ Low Voltage

✔ Excellent Uniformity

✔ Very High Gain (106)

✔ Geiger Mode – Single Photon

⇗ Market Adoption

✔ Low Voltage

✔ Excellent Uniformity

✔ Very High Gain (106)

✔ Geiger Mode – Multi-Photon

⇗Market Adoption

ON Semiconductor ON Semiconductor

Higher Performance Detector = Better Depth Sensing Performance

What is a SPAD/SiPM?“Single photon sensitivity to identify objects in 3D at long distance”

Used to time or count photon arrival

Sensitive to single photons from 200nm to 1000nm (silicon)

Critical figures of merit:

Photon Detection Efficiency (PDE)

Dark Count

Gain/Responsivity

Operating Voltage

Temperature Coefficient

Sensor Uniformity

11

SiPM example created from a

12 microcell SPAD array

Single SPAD based microcell SPAD/SiPM time or count multiple photons

MicroRB-10020-MLP

SiPM Sensor (1590 element SPAD Array)

SensL SPAD/SiPM lead in all categories & are

widely adopted in multiple markets todayPhotons detected by a SPAD

produce a measurable current pulse

Silicon Photomultipliers (SiPMs)

SiPM Technology for LiDAR Applications

12

Automotive Long Distance LiDAR Requirements

13

>200m Ranging

•Low reflective 5% target

•Bright sunlight operation

•Excellent resolution

Compact systems which blend into the vehicle

•Very small apertures possible

•Solid state designs

Lowest cost

•Trend is for more and more IC integration and standard products

•NIR/9xxnm will always be 10x cheaper than SW NIR/1550nm

Modeled performance improvement

of SiPM Sensor vs. APD

Photodetector is a critical component to achieve distance

SiPM: Silicon Photomultiplier

APD: Avalanche Photodiode

SPAD: Single Photon Avalanche Diode

Detectors: SiPMs are becoming the de-facto LiDAR detector

Highest PDE @ 905nm

Gain >1MTight

Uniformity

PPAP Compliant

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• IATF 16949

• AEC Q102

• -40-1050C operation

• Tight uniformity of voltage and gain across millions of sensors

• Required for ease of system calibration and lower mfg. cost

• SiPMs have 10,000 more gain than APD and 1Mx more than PIN Diode

• Cross talk of <20% will provide excellent SNR

• >16% today is best in class for NIR.

• NIR will be the predominate wavelength due to 10x lower cost and large ecosystem

What is new on detector horizon?

Full auto qualification

products to be fully available in Q3 2020

New single pixel, 1D and

2D SiPM, Readout

Circuitry& SPAD Arrays

Lower cross talk/noise

Faster recovery time

More PDE

SYSTEM BENEFIT:

Longer Range OR Less Laser Power

15

ON Semiconductor R-Series SiPM Detector Trend

C-Series

RA-Series

RB-Series

1.5% PDE30% XT

All PDE measurements at 905nm, 22oC room temp;

See datasheets for exact specification

3% PDE30% XT

7% PDE30% XT

RD-Series

10% PDE30% XT

RDM-Series

16% PDE25% XT

FUTURE

Double PDEHalf XT

• 6x improvement during last 3 years

• Future will have another doubling in <2 years

Ph

oto

n D

ete

cti

on

Eff

icie

ncy

(PD

E)

2016 2017 2018 2019 2020 2021-2023

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Recent SiPM Product Announcements

RD-Series 1x1mm SiPM

• Automotive-qualified MLP package, PPAP, IATF 16949

• 10um, 20um, and 35um microcell variants

• Part numbers: MicroRD-100xx-MLP

RDM-Series 1x12 SiPM Array

• Market-leading PDE at 905nm

• Features microlens technology for better PDE and dynamic range

• Automotive-qualified QFN package, PPAP, IATF 16949

• Part number: ArrayRDM-0112A20-QFN

RDM-Series 1x16 SiPM Array

• Market-leading PDE @ 905nm

• Features microlens technology for better PDE and dynamic range

• Automotive-qualified QFN package, PPAP, IATF 16949

• Part number: ArrayRDM-0116A20-DFN

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LiDAR Demonstration Roadmap

Pandion 1.0 Gen-1 Demo & EVK

4Di LiDAR

Flash Illumination (inefficient)

100x100 output:depth & intensity

Limited AoVx

Indoor Operation

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Gen-1 & Gen-2 Demos

Single-point LiDAR

1mm SiPM & Laser

TDC with Multi-shot Histogramming

Outdoor operation

Complete Feasibility

FUSEONE Demo

Multi-point LiDAR

1mm SiPMs & Flash Illumination

Full Waveform Readout

+

AR0231 MARS Camera Overlay

Outdoor Operation

Pandion 1.0 Gen-2 Demo

4Di LiDAR

Flash Illumination with Electronic Scanning

(more efficient)

400x100 output: depth & intensity

Full AoV

Gen-3 Demo

3D LiDAR

1x16 SiPM Array

Galvo Coaxial Line Scanning Illumination

TDC with Multi-shot Histogramming

Outdoor Operation

Proved Feasibility of

SiPMs for dToF LiDAR

LiDAR + Camera;

SiPM Range Advantage

Long Range LiDAR

100m @ 100klux

First SPAD Array LiDAR

& Showcase EVK Use

Addr. VCSEL Array for

Higher Range & Outdoor

DevWare Support Enabled for EVK & Demos

4Di with Pandion SPAD Arrays

19

4D Imaging…?

4Di = Depth + Intensity data from one sensor

20

Why Do SPAD Arrays Matter?

21

Improved angular resolution

•Higher density pixels = higher resolution depth map

Best performance in ambient light (100klux)

•Active circuitry for fastest recovery time

Flexibility for system design

•Usable with scanning or flash illumination

Capability for integration

•One sensor for detecting & readout processing

Rx:

SPAD Array Staring Optics

Tx:

Flash Laser

4D Imaging

•Single photon sensitivity for intensity + depth calculation

Pandion: A 40-Kilopixel SPAD Array

• High-resolution SPAD array

• 400×100 pixels with CMOS Logic

• 1/1.1” optical format (16mm diagonal)

• CMOS functionality provides:• Active reset• In-pixel comparator• Column select• Parallel readout per row

• Output stream of timing pulses (100 channels)

• Signal processing performed off-chip

22

Column Select

Voltage Supply

Ou

tpu

t B

uff

ers

Ro

w A

cce

ss

Control

Signals

Pandion SPAD Array for Direct ToF LiDAR Applications

Pandion LiDAR Configurations

Short Range Configuration

Rx:

Pandion Staring optics

Tx:

Flash Laser

Pandion

SPAD arrayLong Range Configuration

23

Tx:

1D Beam-steering or

Electronic Scanning*

Rx:

Pandion Staring optics

*Addressable VCSEL array synchronized to sensor column readout

Pandion Functional Overview

24

Pandion is a 400×100 SPAD array with CMOS Logic

15.44 mm × 3.86 mm array size (15.92mm diagonal)

CMOS functionality provides

• Active reset

• In-pixel comparator

• Column select

• Parallel readout per row

Output is stream of timing pulses (100 channel)

Signal processing is performed off-chip Column Select

Voltage Supply

Ou

tpu

t B

uff

ers

Ro

w A

cce

ss

Control

Signals

Pandion SPAD Array for 3D ToF Applications Schematic

Pandion Evaluation Kit and LiDAR Demonstration System

25

Power &

Communication

Board

Readout Board

Lens

Mount

SMA-U.FL Cable for

Laser Sync

Lens (not

included)

Standard

Optical

Breadboard

• Calibration

• 4D Imaging

• Histograms

Pandion Short Range Demo Videos

26

Short Range Demo Description:

• Rolling Shutter Flash LiDAR System

• 15m range

• 100x100 res. (crop)

• 27o x 27o FOV

• 808nm flash VCSEL

Pandion Short Range EVK Demo Videos

27

EVK Demo Description:

• Rolling Shutter Flash LiDAR System

• 20m range

• 100x100 res. (crop)

• 10o x 10o FOV

• 850nm flash VCSEL

Pandion EVK with 4Di (Depth + Intensity) Imaging

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Power &

Comms Board

Readout

Board

Custom

CS

mount

Lens

SMA-U.FL

cable

Standard

optical

breadboard

Pandion Evaluation Kit (EVK)

EVK Short Range Demo with 4Di Output: Depth + Intensity

(includes laser, optics, and bandpass filter)

EVK Intensity output with photon counting mode

(passive imaging with lens and no bandpass filter)

Example Application Videos with 4Di

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Industrial (People Counting) Consumer (Gesture Control) Automotive In-Cabin (Driver Monitoring)

Thank you

30

Final Slide

17-Sep-2031

Settling the Great Wavelength Debate

850 / 905 / 940 nm

NIR Spectrum

Detectors: CMOS Si

Lasers: GaAs

1350 / 1550 nm

SWIR Spectrum

Detectors: Typically InGaAs

Lasers: InGaAsP

Shortwave Infrared Spectrum Parameter Near Infrared Spectrum

10x-1000x more expensive:

- Exotic III/V semiconductors for detectors

- Smaller wafer size foundries for lasers

Cost

Will always be cheaper:

- High-vol CMOS silicon foundries for detectors

- Larger wafer size foundries for lasers

Yes, if designed properlyEye Safety

Yes, if designed properly:

- Better detectors = Less laser power

High power laser = complex thermal Thermal Lower laser power = no cooling

Not developed to same extent Ecosystem Many major volume suppliers

Challenged in rain, fog due to water absorption

propertiesAdverse Weather

2x longer distances in case of 25mm of rain in hour

Many components may be controlled ITAR Laser diodes/VCSELs/SiPMs not controlled

Complex/unlikely due to III/V (InG) foundry process Integrated SPAD

Array

Yes, native CMOS process available today

λ

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