ITG_Workshop_2015_Nieweglowski_TUD_IAVT

Transcrição

Institut für Aufbauund Verbindungstechnik
der Elektronik
Fakultät Elektrotechnik & Informationstechnik, Institut für Aufbau- und Verbindungstechnik der Elektronik
Energieeffiziente und adaptive
optische Verbindungen für HighPerformance-Computersysteme
Krzysztof Nieweglowski
XII. ITG-PKM Workshop, Berlin, 20 Mai 2015
Arbeitsrichtungen der IAVT
•
Biokompatible AVT
•
Dickschichttechnik
•
Mikrostrukturcharakterisierung
•
Mikroverbindungstechniken
•
Modellierung, Simulation,
Optimierung von Prozessen
•
Montagetechnologien
•
Optische Verbindungstechnik
•
Qualitätssicherung in der Fertigung
•
Sensoren für zfP und SHM
•
Zerstörungsfreie Prüfverfahren
•
Zuverlässigkeit auf Baugruppenebene
Institut für Aufbauund Verbindungstechnik der Elektronik
XII. ITG-PKM Workshop
Berlin, 20 Mai 2015
Folie 2
Trends für optische Kurzstreckenverbindungen
auf LP-Ebene
Treiber
• wachsender Bandbreitenbedarf
• Motivationsänderung – Kriterien
der Energieeffizienz (mW/Gbps)
und Bandbreitendichte (Gbps/mm2)
Quelle: adaptiert aus –
BPA Report,Optical Backplanes (2000)
Tummala; R.R., Fundamentals of Microsystems Packaging (2001)
Wolter; K.-J.,Vorlesungsskript AVT I (2005)
Kriterium
relative Kosten - Preis-Leistungs-Verhältnis
($/Gbps/ch/m)
 Haupteinfluss - Kosten der Umwandlung
Quelle: adaptiert aus – Fisher, J.: iNEMI Roadmap for Optical Backplanes
(IEEE LEOS 2006)
Berlin, 20 Mai 2015
Folie 3
Optical interconnects in HPC - Roadmap
2008
TODAY
2020
opt. interconnect
rack-to-rack
intrarack
chip-to-chip
on-chip
HPC performance
1 Pflop
10 Pflop
100 Pflop
1 Eflop
# links
40 000
106
107
108
energy efficiency
50mW/Gbps
25mW/Gbps
5mW/Gbps
1mW/Gbps
Source: Vlaslow; Y., (ECOC 2008)
Source: Zheng; X., et al., (ECTC2009)
Reflex Photonics, Sun Microsystems
Source: Offrein; B. J., (ECOC, 2009)
IBM
Source: Vlaslow; Y., (ECOC 2008)
IBM
Berlin, 20 Mai 2015
Folie 4
DFG SFB 912 HAEC -Energy Proportionality
Highly Adaptive Energy-Efficient Computing (HAEC)
Center for Information Services and High Performance
Computing (ZIH)
Measurement at June 20, 2008
Percentage
Goal:
Minimizing Energy
by
Multi-Layer SW/HW
Adaptivity
Rel. Energy Consumption
Rel. Computing Load
Time of Day
Berlin, 20 Mai 2015
Folie 5
High-Rate Inter-Chip Communication
 Chip-to-chip bandwidth limits system
performance
 Hybrid appraoch for intra-rack communication
Optical Interconnect
• adaptive analog/digital circuits
for e/o transceiver
• embedded polymer
waveguide
• packaging technologies
(e.g. 3D stacking of Si/III-V
hybrids)
• 90° coupling of laser
Radio Interconnect
• on-interposer/on-package
• antenna arrays
• analog/digital beam steering
and
interference minimization
• 100Gb/s
• 25 GHz channel @ 200GHz
carrier
• 3D routing & flow
management
Berlin, 20 Mai 2015
Folie 6
Phase I
Phase II
MUX
Retimer &
level control
Clk
Clk/n
LDD
VCSEL
Phase II
PD
TIA
LA
CDR
Clk/n
DEMUX
Energy-adaptive onboard optical links – TP A07
Frequency; Div.




Low power and high speed ICs
Energy/performance adaptivity - load-dependent link performance (closed
energy control loop),
Low loss and high BW board-level planar waveguides and out-of-plane
coupling optics
3D-system integration of optical transceivers for high performance
Berlin, 20 Mai 2015
Folie 7
IC Design for optical TxRx - Circuit adaptivity



Adjustable optical link parameters (trade-off bandwidth vs. power
consumption)
Precise bias control of LDD and TIA
Power optimized circuits for high speed optical links
Adaptive TIA
Berlin, 20 Mai 2015
Folie 8
E/O packaging concept




Onboard overlay flexible optical waveguides
Glass interposer with integrated waveguides
Out-of-plane coupling using 2D-µmirror array – pitch conversion
3D vertical chip stacking - channel cell configuration
Glass PLC
Overlay WGs
Channel cell configuration:

vertical arrangement of
subsequent link components
using TSVs and chip stacking
pitch
conversion
Berlin, 20 Mai 2015
Folie 9
Waveguide structuring at IAVT
1
Waveguide structuring technologies:
1. subtraktive Wellenleiter-in-Kupfer Technologie,
2. additive Wellenleiter-in-Kupfer Technologie,
3. fotolithographisch strukturiert auf ORMOCER®
Basis
2
3
The waveguide-in-copper technology was developed
in collaboration with Fraunhofer-Institute for
Reliability and MicroIntegration (FhG IZM) .
Quelle: Nieweglowski, K. et al., ISSE 2005, ESTC 2010, ECTC 2013
Berlin, 20 Mai 2015
Folie 10
Technology comparison
Berlin, 20 Mai 2015
Folie 11
Tuning of waveguide’s NA
1.560
Goals:

Low loss MM optical waveguides – < 0.1 dB/cm
High bandwidth – BL > 50 Gbit/s m
BW Limitation:

for MM waveguides - intermodal dispersion
𝐵𝐿 ≈
0,5𝐿
𝜎𝑖𝑛𝑡𝑒𝑟𝑚𝑜𝑑𝑎𝑙
= 3,45
NA is the
dominant factor
𝑛𝑐𝑙 𝑐
𝑓𝑜𝑟 𝑁𝑅𝑍 𝑠𝑖𝑔𝑛𝑎𝑙
𝑁𝐴2
𝑁𝐴 =
2
2
𝑛𝑐𝑜
− 𝑛𝑐𝑙
refractive index @ =850 nm

1.555
1.550
0.14
1.545
0.18
1.540
0.22
1.535
0.26
1.530
1.525
1.520
0.0
0.1
Ormocore
Approach:


Fabrication of refractive index
and dimensionally tuned
waveguides
Analysis of the influence of
waveguide design parameters
(NA, width) on WG’s performance
(optical loss, assembly tolerances,
min. bending radius, BER)
numerical aperture
NA
0.2
0.3
0.4
0.5
0.6
0.7
weigth fraction of Ormoclad
0.8
0.9
1.0
Ormoclad
Weight
fraction
[%]
30
0.0043
0.143
8.2
BL
[Gbps
m]
77.9
50
0.0071
0.185
10.6
46.7
70
0.0099
0.218
12.7
33.3
100
0.0141
0.261
15.3
23.3

[-]
NA
[-]
α
[°]
Optical parameters for waveguides with tuned refractive
index of cladding material
Berlin, 20 Mai 2015
Folie 12
Fabrication technology
UV Photopatterning



structuring of polymeric (hybrid) material
using
mask based UV-photolithography
ORMOCER®s - inorganic-organic hybrid
materials:
 Ormocore: nco = 1,550 @ 850 nm
 Ormoclad: ncl = 1,528 @ 850 nm
Test layout with variation of core width and
functional structures as bendings for
derivation of design rules
Cross section of waveguides
Process flow
Berlin, 20 Mai 2015
Folie 13
Optical characterization of WGs
Characterization methods:




Cut-back measurement method
 precise insertion loss
determination
Near-field end face analysis
 mode filling and mode conversion
along the waveguide
Far-field investigations
 beam divergence - numerical
aperture
Bending losses
 min. bending radius vs. NA
Optical transmission measurements
 limitations of optical link at high
data rates
Photograph of experimental set-up
1.1
SI MM-fiber
NA = 0.1
NA = 0.2
1.0
0.9
0.8
norm. optical Power

0.7
0.6
0.5
0.4
0.3
2
1/e
0.2
0.1
0.0
-20
-15
-10
-5
0
5
10
15
20
far-field angle [ °]
far-field of step index fiber launching
Berlin, 20 Mai 2015
Folie 14
Optical characterization - results
0
1dB
1
coupling loss [dB]
2
3dB
3
Results of
assembly
tolerances
measurement for
in-coupling end
face
4
5
horizontal
30µm
40µm
50µm
vertical
30µm
6
7
8
9
10
-30
-20
-10
0
10
20
30
40
50
lateral displacement [µm]
waveguide width
Results of attenuation measurement




NA 
Low loss planar WGs - min. attenuation of
0.024 dB/cm
Validation of NA tuning with near- and farfield analysis
Min. bending radius: 4 – 14 mm
depending on NA
Assembly tolerances: lateral displacement
tolerances from ±10 µm up to ±25 µm
depending on WG’s cross section
Near-field results for 88.5 mm long waveguides
Berlin, 20 Mai 2015
Folie 15
30 Gbit/s
25 Gbit/s
Optical transmission measurements
80 mV/DIV
38 mV/DIV
30 mV/DIV
27 mV/DIV
44 mV/DIV
38 mV/DIV
50 mV/DIV
38 mV/DIV
reference
(w/o WG)
NA:
0.14
0.18
0.22
with optical waveguide (w = 40 µm)
optical eye diagrams @ -3dBm received power
Influence of NA on bit error rate @ 30Gbit/s
63 mV/DIV



Results for data transmission with on-board waveguides:
 Error free transmission (BER < 10-12) up to 30 Gbit/s
 @ 35 Gbit/s  minimum BER > 10-3 (Tx/Rx-module limited)
No significant distortion of eye diagram by insertion of planar waveguide (LWG =
9 cm)
Small influence of NA on BER detected – investigation on longer WGs and
higher speed Tx/Rx-modules needed for exact determination of WG‘s
performance
Berlin, 20 Mai 2015
Folie 16
Waveguides on Flex

Overlay technology for improved yield and flexibility
 planar optical waveguides on flexible substrate (Polyimide
laminate - Kapton® and Zeta®Cap)

Substrate pretreatment for enhancement of adhesion

Handling of flexible material:

temporary bonding – thermal release tape (RevAlpha
3195HS)

stretching using rigid frame/substrate
substrate treatment
PI (Kapton®)
etched PI laminate
(Zeta®Cap)
epoxy
hybrid
epoxy
hybrid
untreated
0
--
--
0
plasma O2
+
--
--
0
plasma O2 & CF4
--
--
--
--
hydrolysis
+
--
--
0
Adhesion test results of the different substrates
Surface energy of differently treated PI substrates
Berlin, 20 Mai 2015
Folie 17
Wafer-level coupling optics


Glass interposer with integrated waveguides and micromirrors –
wafer-level processing
Electrical layers for FC-assembly of E/O devices and chip stacking
Glass
PLC
Overlay WGs
Glass PLC
bottom chip assembly
top chip assembly

90° deflection using TIR – no
selective mirror metallization

no focusing optics/ no thinning needed
(standard thickness of 1,5 mm)

thinning of glass interposer or
additional optics (lenses, optical
TGVs)

cavity in PCB needed

complex technology for metallization
structuring
Berlin, 20 Mai 2015
Folie 18
Wafer-level coupling optics - WGs in glass
 Technology: Ag-ion exchange with E-field
(LEONI)
 Wafer with test structures:
 40 WG-array – coupling optics
 taper structures – mode field adoption
 Lenses, optical TGVs – optical via/throughsubstrate connection
Diffusion of silver
ions in the glass
(source: salt melt
AgNO3); structuring
with hard mask (Al)
Burial of WGs with Efield supported ion
diffusion
(source: salt melt
NaNO3)
source: Ari Tervonen; J. of AP
1990
Cross section of glass-integrated
WGs in Ag-ion exchange process
Top view of glass-integrated WGs
Berlin, 20 Mai 2015
Folie 19
Mirror formation
Wafer sawing
 only straigth cuts possible
 only discrete angle realizable
(defined by blade cross section)
 easy and quick process
 surface roughtness Ra= 0,11 µm
(2000 mesh)
Laser ablation
 enables selective mirror
fabrication
 first tests (3D Micromac):
 surface roughtness Ra= 0,729
µm
 grooved structure caused by
beam scanning
 Process optimization needed for
defined mirror angle
Berlin, 20 Mai 2015
Folie 20
Top chip assembly on glass
 Thinning of glass interposer from standard
thickness of 1,5mm to < 150 µm –
mechanical grinding and polishing
 First tests with 90° deflection using TIR
 coupling loss of ~1,6 dB
(insertion loss of coupling element)
Thickness comparison –
before and after thinning
Top chip assembly
Light deflection on TIR (@850nm)
Berlin, 20 Mai 2015
Folie 21
Summary
 HAEC approch for energy efficient and adaptive C2Cinterconnect
 Board-level planar waveguides with variable NA:
 Low loss planar WGs - min. attenuation of 0.024
dB/cm
 short WGs show no limitation for data rates < 25
Gbit/s
 Influence of waveguide parameters (NA, cross
section) on performance of WGs
 Glass interposer concept for out-of-plane coupling optics
– identification of suitable technologies and first test
structures
Berlin, 20 Mai 2015
Folie 22
Fragen und Kontakt
Vielen Dank für Ihre Aufmerksamkeit !!
Kontakt:
Dr.-Ing. Krzysztof Nieweglowski
 Technische Universität Dresden
Institut für Aufbau- und
Verbindungstechnik der Elektronik
Helmholtzstr. 10
01069 Dresden
 [email protected]
 +49-351-463 35291
 +49-351-463 37035
Berlin, 20 Mai 2015
Folie 23

ITG_Workshop_2015_Nieweglowski_TUD_IAVT

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