A 3D Integrated Circuit is a chip that has active electronic components stacked on one or more layers that are integrated both vertically and horizontally forming a single circuit. In the 3-D design architecture, an entire chip is divided into a number of blocks, and each block is placed on a separate layer of Si that are stacked on top of each other. In a generic 3D IC structure, each die is stacked on top of another and communicated by Through-Silicon Vias (TSVs). Architectural issues Traditional shared buses do not scale well – bandwidth saturation Chip IO is pad limited Physical issues On-chip Interconnects become increasingly slower w.r.t. logic IOs are increasingly expensive Consequences Performance losses Power/Energy cost Design closure issues or infeasibility Reduced wire length Total wire length Larger circuits produce more improvement Lower power per transistor Decreased interconnect delay Higher transistor packing densities Smaller chip areas There are four ways to build a 3D IC: Monolithic Wafer-on-Wafer Die-on-Wafer Die On Die At runtime, thermal variations will introduce additional time-varying clock skew, further increasing design uncertainty 2 - Thermal Issues In 3-D ICs Due to reduction in chip size of a 3D implementation, 3D circuits exhibit a sharp increase in power density Analysis of Thermal problems in 3D is necessary to evaluate thermal robustness of different 3D technology and design options. 3 - Reliability Issues In 3-D ICs Electro thermal and Thermo-mechanical effects between various active layers can influence electro-migration and chip performance Die yield issues may arise due to mismatches between die yields of different layers, which affect net yield of 3D chips. TSV check on reset Control use dedicated Vias in order to establish which vias are corrupted. If 1, 2 and 3 TSVs are OK, the control set the enable signal set_to and set_from: broken path are skipped! Pads routing shift as show in the figure Need to define The handling protocol during the TSVs check 3D IC design is a relief to interconnect driven IC design. Still many manufacturing and technological difficulties Physical Design needs to consider the multiple layers of Silicon available. Optimization of both temperature and wirelength Placement and routing algorithms need to be modified [1] J. Davis, et al., "Interconnect limits on gigascale integration (GSI) in the 21st century," Proceedings of the IEEE , vol.89, no.3, pp.305-324, Mar 2001. [2] Banerjee, K.; Souri, S.J.; Kapur, P.; Saraswat, K.C.; , "3-D ICs: a novel chip design for improving deep- submicrometer interconnect performance and systems-on-chip integration," Proceedings of the IEEE , vol.89, no.5, pp.602-633, May 2001.

1. SEMINAR GUIDE
PRESENTED BY
MISS LATHA R NAIR
TRIPTI KUMARI
ASSISTANT PROFESSOR
REG NO – 12110081
COMPUTER SCIENCE &
ENGINEERING
S7, CSE, SOE, CUSAT
SOE, CUSAT
ROLL NO - 79

2. CONTENTS
INTRODUCTION
WHY 3D
BENEFITS OF 3D INTEGRATION
ARCHITECTURE
MANUFACTURING
PERFORMANCE CHARACTERISTICS
CHALLENGES AND ISSUES
CONCLUSIONS
REFERENCES

3. INTRODUCTION
•
A 3D Integrated Circuit is a chip that has active electronic
components stacked on one or more layers that are integrated
both vertically and horizontally forming a single circuit.
• In the 3-D design architecture, an entire chip is divided into a
number of blocks, and each block is placed on a separate layer
of Si that are stacked on top of each other.
• In a generic 3D IC structure, each die is stacked on top of
another and communicated by Through-Silicon Vias (TSVs).

4. EVOLUTION IN INTEGRATION

5. WHY 3D ?
• Multi-core are
bandwidth-hungry:
• Limited caches
• Multi-threading
• Virtualization
“The Bandwidth Challenge”

6. 2.5D VS 3D IC

7. COMMUNICATION BOTTLENECK
• Architectural issues
• Traditional shared buses do not scale
•
well – bandwidth saturation
Chip IO is pad limited
• Physical issues
• On-chip Interconnects become
•
increasingly slower w.r.t. logic
IOs are increasingly expensive
• Consequences
• Performance losses
• Power/Energy cost
• Design closure issues or infeasibility

8. BENEFITS OF 3D INTEGRATION
• Reduced wire length
• Total wire length
• Larger circuits produce more
improvement
• Lower power per transistor
• Decreased interconnect delay
• Higher transistor packing
densities

9. ARCHITECTURE

10. ARCHITECTURE CONT…
IEEE

11. ARCHITECTURE CONT…

12. MANUFACTURING
•
There are four ways to build a 3D IC:
1. Monolithic
2. Wafer-on-Wafer
3. Die-on-Wafer
4. Die On Die

13. MONOLITHIC
• A technology breakthrough allows the fabrication of
semiconductor devices with multiple thin tiers (<1um) of copper
connected active devices utilizing conventional fab equipment.
• Electronic components and their connections (wiring) are built in
layers on a single semiconductor wafer, which is then diced into
3D ICs.
• There is only one substrate, hence no need for aligning, thinning,
bonding, or through-silicon via.

14. WAFER-ON-WAFER
• Electronic
components are
built on two or more
semiconductor
wafers, which are
then aligned,
bonded, and diced
into 3D ICs.
• Each wafer may be
thinned before or
Detailed view
Generalized view
SOI
wafers
with bulk
substrate
removed
Layer 5
Inter-layer
bonds
Layer 4
Layer 3
1 m
Layer 2
Metal level
of wafer 1
Bulk wafer
Layer 1
Device
level 1
Bulk Substrate
10 m
500 m

15. DIE-ON-WAFER
• Electronic components
are built on two
semiconductor wafers.
One wafer is diced; the
singulated dice are
aligned and bonded onto
die sites of the second
wafer
INTER-LAYER
INTERCONNECT
DICE
WAFER

16. DIE ON DIE
• Electronic components are
built on multiple dice,
which are then aligned and
bonded.
• Thinning and TSV creation
may be done before or after
bonding.

17. 3D FABRICATION TECHNOLOGIES

18. PERFORMANCE CHARACTERISTICS
• Timing
• Energy
• With shorter interconnects in 3D ICs, both switching energy and
cycle time are expected to be reduced

19. PERFORMANCE CHARACTERISTICS
CONT…
• Timing
• In current
•
•
technologies, timing
is interconnect
driven.
Reducing
interconnect length in
designs can
dramatically reduce
RC delays and
increase chip
performance
The graph below
shows the results of a
reduction in wire

20. PERFORMANCE CHARACTERISTICS
CONT…
• Energy
• Wire length
reduction has
an impact on
the cycle time
and the energy
dissipation
• Energy
dissipation
decreases with
the number of
layers used in

21. CHALLENGES AND ISSUES
1- Clock Distribution in 3D
•
2D clock tree very hard but
feasible (H-Tree,
Differential, Single Ended
Clock Distribution)
•
Minimizing the clock skew
of a clock tree in a complex
3D structure is an
extremely challenging task
Clock Root

22. CHALLENGES AND ISSUES CONT…
• At runtime,
thermal variations
will introduce
additional timevarying clock
skew, further
increasing design
uncertainty
high number
of vertical vias

23. CHALLENGES AND ISSUES CONT…
2 - Thermal Issues In 3-D ICs
• Due to reduction in chip size of a 3D implementation, 3D circuits exhibit a sharp increase in
power density
• Analysis of Thermal problems in 3D is necessary to evaluate thermal robustness of different
3D technology and design options.
3 - Reliability Issues In 3-D ICs
• Electro thermal and Thermo-mechanical effects between various active layers can influence
electro-migration and chip performance
• Die yield issues may arise due to mismatches between die yields of different layers, which
affect net yield of 3D chips.

24. RELIABILITY ENHANCEMENT
• TSV check on reset
• Control use dedicated Vias
in order to establish which
vias are corrupted.
• If 1, 2 and 3 TSVs are OK, the
control set the enable signal
set_to and set_from: broken
path are skipped!
• Pads routing shift as show in
the figure
• Need to define The handling
protocol during the TSVs
check

25. CONCLUSION
•
3D IC design is a relief to interconnect
driven IC design.
•
Still many manufacturing and
technological difficulties
•
Physical Design needs to consider the
multiple layers of Silicon available.
•
Optimization of both temperature and
wirelength
•
Placement and routing algorithms need to
be modified

26. REFERENCES
[1] J. Davis, et al., "Interconnect limits on gigascale integration
(GSI) in the 21st century," Proceedings of the IEEE , vol.89, no.3,
pp.305-324, Mar 2001.
[2] Banerjee, K.; Souri, S.J.; Kapur, P.; Saraswat, K.C.; , "3-D ICs: a
novel chip design for improving deep- submicrometer interconnect
performance and systems-on-chip integration," Proceedings of the
IEEE , vol.89, no.5, pp.602-633, May 2001.

27. THANKYO
U

28. QUESTIONS
?
IC