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THREE-DIMENSIONAL INTEGRATED CIRCUITS
As Integrated circuits become more and more miniaturized,
the only direction to go may be … up!
Raymond Do
Rory Nordeen
Ryan Tomita
OVERVIEW
Background
•
Why 3-D?
•
Traditional Integrated Circuit methods, Emergence of 3-D
Manufacturing
•
Major Methods
Benefits
•
What’s so great about 3-Dimensions?
Drawbacks and Challenges
•
Why don’t we see these everywhere?
WHY 3-D?
Comparing semiconductor manufacturing process nodes with some microscopic objects
TRADITIONAL METHODS
•
Highly Pure silicon Wafer substrate
•
Many individual circuits are laid up on
a Silicon wafer substrate
•
Transistors are formed directly in the
substrate, interconnected with wires,
and overlaid with dielectric.
•
Wafer is diced to separate the
individual ICs (Dies)
METHODS FOR 3-D
Four Major methods used
• Monolithic
• Simplest, most limited
• Wafer-on-Wafer
• More complicated integration using multiple wafers
• Die-on-Wafer
• Individual dice are stacked on a single wafer
• Die-on-Die
• Similar to Die-on-Wafer: paired dice are stacked
MONOLITHIC
• Method researched at Stanford University
• Components and connections are made in layers on a single
wafer
• Simplicity: no alignment or inter-layer connection issues
• Limited complexity! Transistor creation processes damage any
existing wiring
WAFER-ON-WAFER
•
3-D “layers” laid up on
independent wafers
•
Wafers aligned, stacked &
adhered to each other
•
Vertical interconnection
made with “through silicon
vias”
•
Reduced yields since one
failed device in an individual
chip fails entire chip
DIE-ON-WAFER & DIE-ON-DIE
Die-on-Wafer
•
Same as Wafer-on-Wafer, only
one Wafer is diced prior to
stacking
•
Additional dice can be added
to the stack
•
Improved yields since
individual dies can be tested
Die-on-Die
• Individual Dice are stacked
and bonded
• Even more Improved yields
since all dice can be tested
BENEFITS
Footprint
Cost
Heterogeneous integration
Shorter interconnects
Power consumption
Security
Bandwidth
Footprint
• Stack components in layers on top of each other
Cost
• Each layer can be designed, tested, and
manufactured independently
Bandwidth
• Interconnects between layers can be wider buses than
2D interconnects
HETEROGENEOUS INTEGRATION
Heterogeneous layers
• Layers can have specific functions
Package size
• Bottom layer keeps original
thickness
• Layers above bottom can be
thinned
• Not much thicker than a single
wafer
SECURITY
Sensitive circuits may be divided among layers
Delayering
•
Circuitry can be hidden between layers
•
Delayering would destroy circuitry
Voltage Imaging
•
Substrates and bonding material would blur and attenuate image
Manufacturing security
•
Components can be spread across different layers
•
Layers can be manufactured at different plants
POWER CONSUMPTION
Important with devices becoming mobile and distributed
Shorter interconnects
Potentially keep more signals on-chip
• Don’t have to drive I/O
CHALLENGES
YIELD
• Manufacturers need to know how 3D IC will impact
yield percentages.
• Extra manufacturing step adds risks for defects.
• Standard factors that affect yield include:
• Die area
• Circuit Density
• Maturity of Process
• Specific factors that affect 3D yield include:
• Extra Processing
• Contamination
• Alignment
• Edge Effects
• Design
HEAT
• Average distance between system components is reduced:
Good for performance but bad for dissipating heat.
• Electrical proximity correlates with thermal proximity.
• Heat building up within the stack must be dissipated, but
how?
• A team from IBM, École Polytechnique Fédérale de
Lausanne (EPFL) and the Swiss Federal Institute of
Technology Zurich (ETH) is working on the issue.
• Microchannels with cooling systems using nanosurfaces that pipe coolants
DESIGN COMPLEXITY
• 3D integration requires sophisticated design
techniques and new CAD tools.
• Full utilization of wafer-thinning and through-siliconvias (TSV) cannot be modeled with current 2D
software.
• No major companies are offering tools.
• Progress is cost-driven.
TSV-INTRODUCED OVERHEAD
• A typical size of TSV is much larger compared to global
wires (1 to 10 μm).
• TSVs take room and increase total chip area.
• TSVs act as obstacles.
• While the usage of TSVs is generally expected to
reduce wire length, this depends on the number of
TSVs and their characteristics.
• TSVs also increase manufacturing cost.
TESTING
• Insufficient understanding of 3D testing issues.
• To achieve high overall yield and reduce costs, separate
testing of independent dies is essential.
• There are serious obstacles to pre-bond testing of wafers in
3D integration.
• Wafer probing is a major limitation for thinned wafers and
pre-bond wafers
• Any given layer in a stacked 3D IC does not always include
complete functionality.
• Methods to test for heat.
• Costly test practices.
LACK OF STANDARDS
• There are few standards for TSV-based 3D-IC design,
manufacturing, and packaging.
• Cost-effective high-volume manufacturing will be
difficult to achieve unless manufacturing standards
are developed.
• SEMI formed a Three-Dimensional Stacked Integrated
Circuits Standards Committee.
• Bonded Wafer Pair (BWP) Task Force
• Inspection and Metrology Task Force
• Thin Wafer Carrier Task Force
REFERENCES
1.
Robert Patti, "Impact of Wafer-Level 3D Stacking on the Yield of ICs" http://www.future-fab.com/documents.asp?d_ID=4415 Future Fab Intl. Volume 23,
2007
2.
"EDA's big three unready for 3D chip packaging" http://www.eetasia.com/ART_8800485666_480300_NT_fcb98510.HTM EE Times Asia October 25, 2007
3.
D. H. Kim, S. Mukhopadhyay, S. K. Lim, “Through-silicon-via aware interconnect prediction and optimization for 3D stacked ICs,” in Proc. of Int. Workshop
Sys.-Level Interconn. Pred., 2009, pp. 85–92.
4.
S. Borkar, “3D integration for energy efficient system design,” in Proc. Design Autom. Conf., 2011, pp. 214–219.
5.
H.-H. S. Lee, K. Chakrabarty, “Test challenges for 3D integrated circuits,” Des. Test. Comput., vol. 26, no. 5, pp. 26–35, Sep 2009
6.
3-D chip stacks standardized" http://www.eetimes.com/electronics-news/4077835/3-D-chip-stacks-standardized EE Times November 7, 2008
7.
"SEMI International Standards Program Forms 3D Stacked IC Standards Committee" http://www.semi.org/en/press/CTR_042145?id=highlights SEMI press
release December 7, 2010
8.
Developer, Shed. "3D Processors, Stacking Core". September 20, 2005. http://www.devhardware.com/c/a/Computer-Processors/3D-Processor-Technology/,
9.
Developer, Shed. "3D Processors, Stacking Core". September 20, 2005. http://www.devhardware.com/c/a/Computer-Processors/3D-ProcessorTechnology/1/
10.
Xiangyu Dong and Yuan Xie, "System-level Cost Analysis and Design Exploration for 3D ICs", Proc. of Asia and South Pacific Design Automation Conference,
2009, http://www.cse.psu.edu/~yuanxie/3d.html
11.
"3D IC Technology Delivers The Total Package" http://electronicdesign.com/article/engineeringessentials/3d_ic_technology_delivers_the_total_package.aspx Electronic Design July 02, 2010
12.
James J-Q Lu, Ken Rose, & Susan Vitkavage “3D Integration: Why, What, Who, When?” http://www.future-fab.com/documents.asp?d_ID=4396 Future Fab
Intl. Volume 23, 2007
13.
William J. Dally, “Future Directions for On-Chip Interconnection Networks” page 17, http://www.ece.ucdavis.edu/~ocin06/talks/dally.pdf Computer Systems
Laboratory Stanford University, 2006
14.
Johnson, R Colin. "3-D chip stacks standardized". July 10, 2008. http://www.eetimes.com/electronics-news/4077835/3-D-chip-stacks-standardized
15.
"3D-ICs and Integrated Circuit Security" http://www.tezzaron.com/about/papers/3D-ICs_and_Integrated_Circuit_Security.pdf Tezzaron Semiconductor, 2008
16.
Dong Hyuk Woo, Nak Hee Seong, Dean L. Lewis, and Hsien-Hsin S. Lee. "An Optimized 3D-Stacked Memory Architecture by Exploiting Excessive, High-Density
TSV Bandwidth." In Proceedings of the 16th International Symposium on High-Performance Computer Architecture, pp.429-440, Bangalore, India, January,
2010.
17.
"Predicting the Performance of a 3D Processor-Memory Chip Stack" Jacob, P., McDonald, J.F. et al.Design & Test of Computers, IEEE Volume 22, Issue 6,
Nov.–Dec. 2005 Page(s):540–547