3D integrated circuits stack active electronic components in multiple layers within a single circuit to reduce wasted space and improve interconnectivity between components. This allows both homogenous and heterogeneous chips to be accommodated. The substrate is divided into tiers with similar components stacked together to ease interconnections. Fabrication methods include beam recrystallization, processed wafer bonding, and solid phase crystallization. Routing in 3D considers multiple layers and placement of inter-wafer vias to reduce delays. MAGIC layout editing software provides bonding commands to treat layered designs as single entities. 3D ICs provide significant improvements over conventional 2D designs.

2.  3D Integrated circuit is a chip which accommodates
two or more layers of active electronic components
 They are integrated both horizontally and vertically
onto a single circuit.

3. To reduce wastage of space on the substrate.
To improve interconnections among different wafers.
To reduce the length of interconnections which in turn
reduces heat dissipation and also RC delays.
Can be used to accommodate both homogenous and
heterogeneous chips.
Thus there is a great urge to switch over
from 2D ICs to 3D ICs

4. •The substrate is divided into blocks
•The similar characterized active components are stacked
in the same block.
•This results in ease of interconnection.
•Each block is called a tier.

5. LOCAL TIERS
•Independent responding blocks
SEMI-GLOBAL TIERS
•Blocks used for intra communication
GLOBAL TIERS
•Inter communicating blocks used for clock and power supply

6. BEAM RECRYSTALLISATION:
This method involves deposition of polysilicon.
This is used to fabricate TFTs which in turn are used in
fabrication of 3D ICs.
PROCESSED WAFER BONDING:
This method bonds processed wafers together, and it is
independent of temperature.
SOLID PHASE CRYSTALLISATION:
It offers flexibility for fabricating multiple layers, used
mostly for stacking SRAM and EPROM.

7. Timing
Energy performance
Interconnection structures

8. In current technologies, timing is interconnect driven.
Reducing interconnect length in designs can dramatically
reduce RC delays and increase chip performance

9.  Wire length reduction has an impact on the cycle
time and the energy dissipation
Energy dissipation decreases with the number of
layers used in the design

11. 3D Cell Placement
Placement by min-cut partitioning
3D Global Routing
Inter-wafer vias
Circuit layout management
MAGIC

12. Natural to think of a 3D
integrated circuit as being
partitioned into device
layers or planes
Min cut partitioning
along the 3rd dimension is
same as minimizing vias

14. •Routing in 3D consists of routing a set of aligned
congruent routing regions on adjacent wafers.
•Wires can enter from any of the sides of the routing
region in addition to its top and bottom
•3D router must consider routing on each of the layers
in addition to the placement of the inter-waver vias

15. ILLUSTRATION OF ROUTING AREAS
y y
x x
z z
Detailed routing of net when
routing areas are known
LOOSE ROUTING DETAILED ROUTING

16.  MAGIC is an open source layout editor developed at UC Berkeley
 It is an extension to MAGIC by providing support for Multi-layer
IC design.
 The difference is that it has a new Command “bond”.
 Bond places inter-layer vias in the design file.
 Once Two layers are bonded they are treated as one entity.

17. The 3D Integrated circuits are a great relief to
interconnected IC technologies.
 This opens up a new era in chip designing which has
many aspects still to be explored and exploited.
These can be used in many facets of our lives like
smartphones,microprocessor based memory stacks etc.
Thus it can be concluded that
“3D IC – A GREAT UPLIFTMENT TO IC WORLD”