cobra - JePPIX

JePPIX Course
Processing
Introduction
Huub Ambrosius
COBRA/NanoLab@TU/e
Photonic Integration: Motivation
• Greatly reduced component cost
•
•
Monolithic interconnection of device elements
Simpler packaging and assembly, standard processes
• High reliability
•
Less interfaces
• High functionality
•
Many more functional elements per chip, higher creativity in design
• High phase stability, excellent device matching
•
Permits interferometric structures
• Robust
•
Single chip designs with minimal optical interfaces are ideal for
demanding environments
• Better power efficiency
•
Minimize optical power loss at interfaces between device elements
On the other hand, the capital and R&D investment needed to play at the
top level in this field is very large (More that 100M€)
JePPIX course 2014 Introduction
2
COBRA
COBRA
Communication Technologies:
Basic Research and Applications
COBRA staff
~25 scientific staff & technicians
~25 postdocs
~50 PhD
Core
Materials (PSN)
Components (PhI)
Systems (ECO)
800 m2
cleanroom
JePPIX course 2014 Introduction
3
COBRA
NanoLab@TU/e
• NanoLab@TU/e is the name of the clean-room facility
and COBRA is using this clean-room
• 800m2 clean-room + 800 m2 subfab (service area with
pumps etc)
• Facilities are open for external institutes and
companies.
JePPIX course 2014 Introduction
4
COBRA
Generic Integration Philosophy
Basic Building Blocks
A
Optical Amplifier
Transistor
j
Resistor
Phase Modulator
P
Capacitor
Polarisation Converter
Electrical connection
Waveguide
Electronic
integration
Photonic
integration
JePPIX course 2014 Introduction
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COBRA
All kinds of passive devices …
MMI-couplers and filters
MMI-reflectors
AWG-demux
ring filters
polarization splitters
polarization combiners
polarization independent
differential delay lines
JePPIX course 2014 Introduction
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COBRA
All kinds of lasers …
Fabry-Perot lasers
tunable DBR lasers
multiwavelength lasers
picosecond pulse laser
ring lasers
JePPIX course 2014 Introduction
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> 25 mW output power
< 100 kHz line width
< 1 ps pulse width
…
COBRA
switches and modulators …
phase modulator
> 40 GHz bandwidth
> 50deg/V.mm
amplitude modulator
fast space switch
polarization independent 2x2 switch
ultrafast switch
WDM crossconnect
WDM add-drop
JePPIX course 2014 Introduction
8
COBRA
Examples of Photonic ICs by COBRA
multiwavelength laser
WDM TX
Tunable
WDM-TTD switch WDM laser
optical crossconnect
JePPIX course 2014 Introduction
wavelength converter
9
picosecond
pulse laser
COBRA
1x16 AWG Switch
Multi Project Waferruns in InP
• With a Generic Process you can do Multi Project
Wafer runs
• Several users on one wafer batch, making the initial
development costs relative low!!
• Different applications of ASPICs (Application Specific
Photonic Integrated Circuit)
• Up to 12 users on a full 2”wafer
• 56 chips of 4 x 4 mm2
• Sofar MPWs have been done at OCLARO, Fraunhofer
HHI and COBRA
JePPIX course 2014 Introduction
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COBRA
Recent ASPICs EuroPIC, PARADIGM,
MEMPHIS
WDM receiver for FTTH
(user Genexis, fab HHI)
Filtered Feedback MW laser
(user ASTRON, fab Oclaro)
4x4 space and l-selective switch
(user TU/e, fab COBRA)
hybrid TDM-WDM transmitters
(user Genexis, fab Oclaro)
Pulse serialiser
for KM3NeT neutrino detector
(user NIKHEF, fab Oclaro)
Pulse regenerator
(user U Pisa, fab COBRA)
non-telecom
telecom
JePPIX course 2014 Introduction
11
COBRA
FBG-readout
(user Fibresensing, fab HHI)
Pulse shaper
for bio-imaging
(user UTwente, fab Oclaro)
MPW run at COBRA
14 different designs:
- 2 x TU/e ECO
- 3 x TU/e PhI
- 3 x WUT (Poland)
- 1 x UEST (China)
- 2 x University of Bristol
- 1 x Scuola Superiore Sant'Anna
- 1 x Bright Photonics
- 1 x NIKHEF
• Full 2” Processing
Processed wafer
Mask Design
JePPIX course 2014 Introduction
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COBRA
The General COBRA flow
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
Epi 1 (active structure)
Litho 1 (active-passive)
Etch 1 (wet etch)
Epi 2 (passive strucure)
Removal mask and epi 3 (contact structure)
Removal protecting layer
Deposition 50 nm SiNx
Positive resist for waveguide definition
Waveguide litho
Nitride etch
Resist removal
Resist for deep area definition
JePPIX course 2014 Introduction
PAGE 13
COBRA
The general COBRA flow (2)
13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
Lithography for deep area’s
Etching difference between shallow and deep area’s
Resist removal
Etching of all waveguides
Resist for definiton isolation etch
Lithography for isolation area
SiNx from isolation section
Resist removal
Etching isolation cladding
Mask contact areas (PHM’s and SOA’s)
SiNx removal
Resist removal
JePPIX course 2014 Introduction
PAGE 14
COBRA
The General COBRA flow (3)
25)
26)
27)
28)
29)
30)
31)
32)
33)
Etching InGaAs and InP
SiNx removal from contact area’s
Planarization with Polyimide or BCB
Etch back of polyimide or BCB
Photoresist for metal lift off
Lithography for contact metallization
Ti/Pt/Au metallization
Lift off process
Plating (thicker contact metal) and back side metallization
JePPIX course 2014 Introduction
PAGE 15
COBRA
Active/Passive Integration: Epi 1
SixNy
p-InP
i-Q1.25
i-Q1.55
n--Q1.25
n-InP
InP substrate
JePPIX course 2014 Introduction
16
COBRA
Active/Passive Integration: Epi 2
SixNy
p-InP
i-InP
i-Q1.25
i-Q1.55
n--Q1.25
n--Q1.25
n-InP
InP substrate
JePPIX course 2014 Introduction
17
COBRA
Active/Passive Integration: Epi 3
p+-Qtop
surface
p+-InP
p-InP
p-InP
i-InP
i-Q1.25
i-Q1.55
n--Q1.25
n--Q1.25
active
n-InP
InP substrate
JePPIX course 2014 Introduction
18
COBRA
passive
Basic building blocks in the COBRA process
SOA
Shallow etched
waveguide
JePPIX course 2014 Introduction
Deep etched
waveguide
19
Phase
Modulator
Polarisation
converter
COBRA
Tunable
DBR grating
Definition waveguides
JePPIX course 2014 Introduction
20
COBRA
Definition waveguides: Silicon Nitride Mask
JePPIX course 2014 Introduction
21
COBRA
Definition waveguides: Etching difference
between shallow and deep area’s
JePPIX course 2014 Introduction
22
COBRA
Definition waveguides: Etching all waveguides
JePPIX course 2014 Introduction
23
COBRA
Definition waveguides: Mask removal from
isolation sections
JePPIX course 2014 Introduction
24
COBRA
Definition waveguides: Etching Isolation
sections
JePPIX course 2014 Introduction
25
COBRA
Definition waveguides: Mask removal from
passive waveguides
JePPIX course 2014 Introduction
26
COBRA
Definition waveguides: Etching InGaAs from
passive waveguides
JePPIX course 2014 Introduction
27
COBRA
Definition waveguides: Mask removal from
contact area’s
JePPIX course 2014 Introduction
28
COBRA
Metallization: Planarization by Polyimide or
BCB
JePPIX course 2014 Introduction
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COBRA
Metallization: n- and p-side (via lift off
technique)
JePPIX course 2014 Introduction
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COBRA
Further processing
• Further processing needs the following steps:
•
•
•
•
Separation by scribe and break method
AR and/or HR coating if needed
Testing test structures
Testing ASPIC’s if asked by customer
• Packaging is not included in COBRA platform and
has to outsourced.
JePPIX course 2014 Introduction
31
COBRA
MPW run at COBRA
• Last COBRA run: Full 2” Processing
Processed wafer
Mask Design
JePPIX course 2014 Introduction
32
COBRA
Band Gap vs Lattice Parameter
3.0
5.868Å
6
AlN
Diamond
bandgap [eV]
5
2.5
bandgap [eV]
2.0
4
GaN
3
2
1
InN
Al2O3
0
2,0
1.5
GaAs
3,0
GaAs
InAs InSb
4,0
5,0
lattice constant [Å]
InP
1.30mm
1.55mm
1.0
GaSb
0.5
6,0
direct
indirect
0.0
5.2
JePPIX course 2014 Introduction
5.6
InAs
6.0
lattice constant [Å]
PAGE 33
InSb
6.4
COBRA
6.8
Energy Bandgap
JePPIX course 2014 Introduction
PAGE 34
COBRA
Energy Bandgap
l (µm) = 1.24/Eg (eV)
Energy Band Gap of Ternary Alloys AxB(1-x)C
E ( x) = xE AC + (1 - x) E BC - cx(1 - x)
Energy Band Gap of Quaternary Alloys AxB(1-x)CyD(1-y)
E ( x, y ) = xyE AC + x(1 - y ) E AD + (1 - x) yE BC + (1 - x)(1 - y ) E BD
- c ABC x(1 - x) y - c ABD x(1 - x)(1 - y ) - c ACD xy (1 - y ) - c BCD (1 - x) y (1 - y )
JePPIX course 2014 Introduction
PAGE 35
COBRA
Clean Room Environment
FED STD 209E classification
maximum particles/ft³
Class
≥0.1 µm
≥0.2 µm
≥0.3 µm
≥0.5 µm
1
35
7
3
1
ISO 3
10
350
75
30
10
ISO 4
750
300
100
ISO 5
100
≥5 µm
ISO
equivalent
1,000
1,000
7
ISO 6
10,000
10,000
70
ISO 7
100,000
100,000
700
ISO 8
JePPIX course 2014 Introduction
PAGE 36
COBRA
ISO classification of clean rooms
maximum particles/m³
Class
≥0.1 µm
≥0.2 µm
≥0.3 µm
≥0.5 µm
≥1 µm
≥5 µm
FED STD 209E
equivalent
ISO 1 10
2
ISO 2 100
24
10
4
ISO 3 1,000
237
102
35
8
Class 1
ISO 4 10,000
2,370
1,020
352
83
Class 10
ISO 5 100,000
23,700
10,200
3,520
832
29
Class 100
ISO 6 1,000,000
237,000
102,000
35,200
8,320
293
Class 1000
ISO 7
352,000
83,200
2,930
Class 10,000
ISO 8
3,520,000 832,000
29,300
Class 100,000
ISO 9
35,200,00
8,320,000 293,000 Room air
0
JePPIX course 2014 Introduction
PAGE 37
COBRA
JePPIX Course
Processing
Vacuum Technology
Huub Ambrosius
COBRA/NanoLab@TU/e
Vacuum Notions
From Latin: “vacuus” means empty
At very low artificial pressure:
still have hundreds of molecules
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COBRA
Vacuum
• There’s nothing in it!
Particles m-3
2.5 x 1025
Atmosphere
2 x 1025
Vacuum Cleaner
Wet Etching JePPIX course 2014
Freeze dryer
1022
Light bulb
1020
Thermos flask
1019
TV Tube
1014
Low earth orbit (300km)
1014
SRS/Diamond
1013
Surface of Moon
1011
Interstellar space
105
PAGE 40
COBRA
Vacuum Units
• Vacuum – sub atmospheric pressure
• SI Unit – Pascal (1Nm-2)
• Atmosphere ~105 Pa
• In Europe – mbar (100 Pa)
• In USA/Asia – Torr (133 Pa)
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COBRA
Vacuum
• Much ado about nothing!
• Nature abhors a vacuum
• We have to work quite hard to get low pressures
− Understand limitations
− Outgassing
− “Pumping”
− Careful design and operation of vacuum systems
− Performance (specification)
− Economics
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COBRA
Vacuum Notions
• Molecular density, n : is the average number of molecules
per unit volume
• Mean free path, l : is the average distance that a molecule
travels in a gas between two successive collisions with
other molecules of that gas
• Time constant to form a monolayer, t : is the time required
for a freshly cleaved surface to be covered by a layer of the
gas of one molecule thickness.
This time is given by the ratio between the number of
molecules required to form a compact monolayer (about
8x1014 molecules/cm2) and the molecular incidence rate f
(at which molecules strike a surface).
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COBRA
Vacuum
P (Torr)
n (molec/cm3)
f (molec
l (cm)
t (sec)
/cm2.sec)
760
2,46 x 1019
2,88 x 1023
6,7 x 10-6
2,9 x 10-9
1
3,25 x 1016
3,78 x 1020
5,1 x 10-3
2,2 x 10-6
10-3
3,25 x 1013
3,78 x 1017
5,1
2,2 x 10-3
10-6
3,25 x 1010
3,78 x 1014
5,1 x 103
2,2
10-9
3,25 x 107
3,78 x 1011
5,1 x 106
2,2 x 103
10-12
3,25 x 104
3,78 x 108
5,1 x 109
2,2 x 106
10-15
3,25 x 10
3,78 x 105
5,1 x 1012
2,2 x 109
Values of molecular density n, molecular incidence rate f,
mean free path l, and time to form a monolayer t, as a
function of pressure P, for air at 25°C.
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COBRA
Vacuum
Ideal (perfect) Gas Theory
pV = nRT (Boyle equation)
p = pressure, V = volume of enclosed space,
n = number of molecules in enclosure,
R = universal gas constant, T = temperature in °K.
At standard conditions of pressure and temperature
(760 Torr and 273,16 °K)
R = 8,314 Joule/°K.mole (~2 cal/°K.mole)
1 Pa = 7.6 mTorr
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COBRA
Vacuum
Avogadro demonstrated that at standard conditions one mole
(molecular weight) of any gas occupies a volume of 22,415 liter.
One mole = Avogadro number NA of molecules
NA = 6,023 x 1023
The mean free path is given by:
l=
kT
2pd 2 p
K=Boltzmann’s constant, d is the gas molecule diameter
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COBRA
Vacuum
Gas
f (molec/cm2.sec)
l (cm)
t (sec)
H2
14,4 x 1017
9,3
1 x 10-3
He
10,4 x 1017
14,7
2,3 x 10-3
N2
3,85 x 1017
5,0
2,1 x 10-3
O2
3,60 x 1017
5,4
2,4 x 10-3
Ar
3,22 x 1017
5,3
2,6 x 10-3
Air
3,78 x 1017
5,1
2,2 x 10-3
H2O
4,80 x 1017
3,4
1,1 x 10-3
CO2
3,07 x 1017
3,3
1,7 x 10-3
Values of f, l and t for various gases at 25°C and 10-3 Torr
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COBRA
Vacuum
Vacuum ranges and their physical characteristics
• Low (and medium) vacuum – P extends from atmosphere
to 10-2 Torr. Main content is Air
• High vacuum – P ranges from 10-3 to 10-7 Torr (mean free
path). Main content is water vapour and as pressure
decreases it becomes CO.
• Ultra high vacuum – P extends from 10-7 to 10-16 Torr (t is
equal or large). Main content is H2
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COBRA
Vacuum in Space
Temperature
1,00E+07
1600
1,00E+05
1400
1,00E+03
1200
1000
1,00E+01
800
1,00E-01
600
1,00E-03
400
1,00E-05
200
1,00E-07
0
-5
0
2,5
7
20
60
200
Altitude (km)
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COBRA
600
Temperature (°K)
Pressure (P)
Pressure
Vacuum
In semiconductor industry vacuum is used:
• Epitaxial Growth (MBE and MOVPE)
• for plasma processes (etching or deposition)
• for coating processes by means of evaporation or
sputtering (metals or dielectrics). The coating processes
operate at a rather low pressure, which mean rather large
mean free paths that help avoiding collisions between the
metal/dielectric molecules.
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COBRA
Vacuum
The gas molecules are assumed to be:
1. hard spheres
2. their volume is very small compared with the volume
occupied by the gas
3. the molecules do not exert forces upon each other
4. moves randomly in rectilinear paths between collisions
5. make perfectly elastic collisions.
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COBRA
Boiling Temperature in Vacuum
At lower pressure: introduction
of vapour pressure
800
700
Pressure (Torr)
The normal boiling point of a
given substance is the
liquefaction temperature at
one atmospheric pressure.
Vapour pressure of water vs
Temperature
600
500
400
300
Liquid
200
Vapour
100
0
0
40
60
80
Temperature (°C)
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COBRA
100