cross thz imaging - israel institutes of...

© 2013 IBM Corporation

Cross THz Imaging

Evgeny Shumakher, Dan Corcos, Noam Kaminsky, Danny Elad IBM Haifa Research Lab Thomas Morf, Bernhard Klein IBM Zurich Research Lab

IBM Research

Technion 2nd THz Imaging Workshop, March 4th 2013 © 2013 IBM Corporation 2

Outline

Background and motivation

Lower terahertz band

System level considerations

RFIC Design and characterization

Interconnect and antenna design

Higher terahertz band

Main challenges

Technology and MEMS post-processing

Antenna design and characterization

Pixel optimization and initial characterization results

IBM Research


Perspective applications

Image by Millivision

Good weather photo

Good weather mm-wave image

Bad weather photo

Bad weather mm-wave image

Apparel fit Security screening Landing/Navigation aid

Image by Enea

Dental/Medical imaging

IBM Research


State of the art

Cryogenically cooled systems

Very high cost and complexity

High sensitivity

Liquid Helium/Cryocompressor cooling

IPHT Jena

Uncooled passive systems

Compact, power efficient, safe

IBM Research

Active imaging system

Requires illumination with THz sources

High image contrast

Public concern about safety risks

L3 Comm.

IBM Research


Higher THz band (0.5 – 1.5 THz) – EU FP7 TeraTOP

Antenna and pixel design

CMOS-SOI

MEMS (LETI in TeraTOP)

Read-out circuitry (CSEM in TeraTOP)

Focusing

optics

DSP (image processing)

Target Si Chip Control

interface

Ima

ge

by Q

ine

tiQ

Staring Focal Plane Array (FPA)

Readout

Lower THz band (0.1 – 0.3 THz)

Antenna and packaging

SiGe RFIC

Read-out circuitry

Image processing

IBM Imaging Technologies


Lower THz band

130 GHz Dicke radiometer in SiGe

IBM Research


Dicke-radiometer based FPA

Primary

reflector

Secondary

reflector

D

Primary

reflector

Secondary

reflectorReceiver

complex

Close-up

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

Clo

se

-up

IBM Research


Dicke-radiometer state of the art

Reference Year Technology Integration Frequency NETD

Voinigescu, U

Toronto

2012 0.13um SiGe

BiCMOS, STM

LNA+PD 160 – 170 GHz 0.35 K

Rebeiz, UC SD 2010 8HP, IBM DS+LNA+PD 84 – 99 GHz 0.83 K

Heydari, UC Irvine 2010 0.18um SiGe

BiCMOS, Jazz

DS+LNA+PD 70 – 96 GHz 0.4 K

Voinigescu, U

Toronto

2009 65 nm CMOS,

STM

DS+LNA+PD 81 – 93 GHz 0.55 K

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

IBM Research


Specifications

Standard IBM 0.13um SiGe Technology fT/fMAX ~ 180/220 GHz

5 layer metallization

MiM capacitors available

Packaging losses < 3 dB Dicke-switch

< 3 dB insertion loss

> 15 dB on-off extinction ratio

LNA Gain of 25-30 dB

Bandwidth of 15 – 20 GHz

NF < 10 dB

Power detector NEP < 5 pW/Hz1/2

General design constraints 1. Consumed power

2. Allocated area

Silicon substrate

CPWG

Transmission line

GND

Side

shielding

Auxillary routing

MoM capacitors

IBM Research


Dicke switch

RFIN

RFOUT

50

SE

S SE

SPDT topology

3 versions of Switching Element

designed

Single 120 um Triple-well NFET

Double 60 um Triple-well NFET

Triple 36 um NPN HBT

350 um

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

IBM Research


Dicke switch

80 90 100 110 120 130 140 150 160-25

-20

-15

-10

-5

0

Frequency [GHz]

|S21|

[dB

]

STW

DTW

HBT

ON

OFF

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

IBM Research


4 cascode + 2CE stage LNA

RF Match

RF C/M RF C/M RF C/M RF C/M

VCC

Vb12

Vb11

Vb21

Vb22

Vb31

Vb32

Vb41

Vb42

RF C/M

Vb51

Vb52

Current re-use

CE

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

400 um

IBM Research


4 cascode + 2CE stage LNA

110 120 130 140 150 160-40

-30

-20

-10

0

10

20

30

Frequency [GHz]

|S-p

ara

mete

rs| [d

B]

S11

S21

S22

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

IBM Research


Power detector

Vb

RF Trap

RF Match

RFIN

VCCVBB VCC

Vb

RF Trap

RF Match

VBB VCC

KQ Resistor

RFIN

Vb

120 um

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

IBM Research


Power detector

10-7

10-6

10-5

10-4

103

104

105

Incident power [W]

Resp

osiv

ity [

V/W

]

meas

sim

103

104

105

10-8

10-7

Frequency [Hz]

VS

D [

V/

Hz]

HzpWNEP 5

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

IBM Research


Package design

Flip-chip

Low loss ( < 1.5 dB)

Small space – a little bigger than chip size

Pads do not have to be only on the periphery

Easy to dissipate heat in our application

10.00 40.00 70.00 100.00 130.00 160.00Freq [GHz]

-1.75

-1.50

-1.25

-1.00

-0.75

-0.50

-0.25

0.00

dB

(S(C

PW

_p

ort

,ms

trip

))

Ansoft LLC gold_stud_matchS21 ANSOFT

Curve Info

dB(S(CPW_port,mstrip))Setup1 : Sw eep1L='-2mil'

IBM Research


-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

110 115 120 125 130 135 140

Frequency [GHz]

Ins

ert

ion

lo

ss

[d

B]

Simulation

Material A

Material B

Material C

Antenna design

Per-pixel antenna

Wide-band horn antenna

Microstrip to waveguide

interconnect

Simple package design

Good results at 120GHz


Upper THz band (EU FP7 TeraTop)

Uncooled antenna-coupled MOSFET

bolometer in CMOS-SOI-MEMS

IBM Research


The challenge

Detect radiation at 0.5 – 1.5 THz with NETD = 1 [K]

Very low frequencies compared to optical waves (like visible and infrared)

Spontaneous emission (in the THz range) is 1/1000 with respect to the IR

Still too high for solid-state electronics (perhaps in the future ?)

THz

Wavelength

Rad

iate

d p

ow

er

Body temperature

IR

IBM Research


Proposed solution

Antenna Coupled Thermal Detector THz radiation is received by an antenna

Power is dissipated in a matched load resistor

The pixel’s temperature rises

A current variation is detected in the integrated transistor

THz

Antenna

Transistor

Load

IBM Research


Main challenges

Sophisticated antennae are needed

Broadband – collect as much in-band signal as possible

Light-weight – low thermal constant (required for video frame rates)

High directivity – FPA optics overlap (and spill-over) over the band

Low cross-talk – resolution

Narrow BW 500-580 GHz Broad BW 500-1000 GHz Original temperature map

Image simulations including detector NEP = 25 pW

IBM Research


Antenna design

Absorption simulations New methodology for simulating accurately antenna-coupled sensors

– Based on modal reflection coefficients

– Patent filed

Maximize the absorption of THz signal

Octagonal skirt antenna

Ab

so

rpti

on

eff

icie

nc

y

Frequency (THz)

IBM Research


Antenna design

Transmission simulations

Evaluate radiation pattern across the band

Cloverleaf antenna

0.6THz 1THz 1.4THz

IBM Research


Technology

Standard IBM 0.18 μm CMOS-SOI process BOX thickness 1μm

4 metal layers as built-in masks

MEMS post-CMOS process Front side dry etching

Metal mask wet etch

Back side wet etching

b) RIE

c) Wet etch

a) CMOS Fab

d) DRIE

IBM Research


MEMS post-processing

The antennas are still planar after release

The holding arms are upwards bent

This is fine as long as they don’t touch

Cloverleaf (2 arms) Log-spiral (α = 0.25) Log-periodic (2 arms)

IBM Research



IBM Research



Fully released 13x9 array

High mechanical yield

High functional yield

IBM Research


Antenna characterization

Measurement of radiation

pattern at 0.65 THz

Pixels outside of Dewar for

avoiding reflections on the

walls

Measurements performed

without vacuum

Resulted in lower responsivity

Test board

THz source

2 axes

rotational stage

IBM Research


Antenna characterization

Several types of antenna tested

Good agreement with HFSS

75º measured HPBW (vs. 80º simulated)

XZ plane YZ plane

IBM Research


10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

100

101

102

103

104

105

106

Responsiv

ity, R

V(f

FR)

[V/W

]

W/L=3.2/0.32

30W/L=96/0.32

W/30L=3.2/9.6

W/100L=3.2/32

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-10

10-9

10-8

10-7

10-6

10-5

10-4

Inte

gra

ted n

ois

e, V

n2 [V

]

W/L=3.2/0.32

30W/L=96/0.32

W/30L=3.2/9.6

W/100L=3.2/32

ROIC

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-12

10-11

10-10

10-9

10-8

10-7

10-6

Drain Current, IDS

[A]

NE

P [W

]

W/L=3.2/0.32

30W/L=96/0.32

W/30L=3.2/9.6

W/100L=3.2/32

Sensor design

Sensitivity is

defined as

Goal NEP = 5 pW

Optimization

Transistor sizing

Transistor biasing

Read-out method

– Suppress/reduce

1/f noise

V

n

R

vNEP

2

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

100

101

102

103

104

105

106

Responsiv

ity, R

V(f

FR)

[V/W

]

W/L=3.2/0.32

30W/L=96/0.32

W/30L=3.2/9.6

W/100L=3.2/32

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-10

10-9

10-8

10-7

10-6

10-5

10-4

Inte

gra

ted n

ois

e, V

n2 [V

]

W/L=3.2/0.32

30W/L=96/0.32

W/30L=3.2/9.6

W/100L=3.2/32

ROIC

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-12

10-11

10-10

10-9

10-8

10-7

10-6

Drain Current, IDS

[A]

NE

P [W

]

W/L=3.2/0.32

30W/L=96/0.32

W/30L=3.2/9.6

W/100L=3.2/32

Different

sensor’s

dimensions

Different

sensor’s

dimensions

Different

sensor’s

dimensions

IBM Research


Pixel characterization

Responsivity (in air)

Good fit to the simulated data

Responsivity in vacuum is about 103

higher

Response time (in vacuum)

Measured on released clover-leaf

antenna

Heating the pixel with a short current

pulse

τ is defined as the 1/e time

≈ 53ms

Thermal time constant in vacuum

After release

IBM Research


Acknowledgements

Dr. Eran Socher, Tel Aviv University

D-band measurement facility

IBM Tokyo Research Lab

D-band flip-chip interconnect mechanical and thermal design

Prof. Ullrich Pfeiffer, University of Wuppertal

THz antenna characterization

The European Union 7th Framework Program

TeraTOP Project

IBM Research


Summary

Key components of a 130 GHz Dicke-radiometer

Realized in standard 0.12 μm SiGe process

Designed for incorporation into very large FPA

Dicke-switch (SPDT)

< 3 dB insertion loss

> 12 dB extinction ratio

LNA

4 cascode + 2 CE stage : > 24 dB gain in 20 GHz bandwidth

Noise figure characterization pending

PD

Demonstrated with NEP ≈ 5pW/Hz1/2

Packaging

Coupling losses < 3 dB

IBM Research


IPHT Jena, 2008 Si-based “near future”

• Cryogenically cooled bolometers

• Purely mechanical scanning • FPA of 50 x 50 sensors

• Video frame-rate

How can “big-silicon” help ?

Primary

reflector

Secondary

reflector

D

Primary

reflector

Secondary

reflectorReceiver

complex

Close-up

LNA

ANT

on

PCKG

DSPD

OUTanlg

ROI

INRF

RX

DATA + CTRL

ANT

NS

SPI

Clo

se

-up

cross thz imaging - israel institutes of...

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