Three Dimensional Integrated Circuits (3D IC) Technology
Improvements to achieve using 3D-IC
There are many plus points to use 3D IC technology such as it provides reduced interconnect delays(R , L , C), higher clock rates .Then it also provides reduced interconnect capacitance(I/O pads), lower power dissipation, higher integration density may go heterogeneous, high bandwidth micro-processors.3D IC technology merges different process technologies, mixed materials, system integration and advanced focal planes.
THROUGH SILICON VIAS (TSV)
TSV is a vertical electrical connection that passes completely through a silicon wafer. TSV are currently considered to be high performance interconnect techniques and primary purpose of TSVs is to create 3D ICs . They are used as an alternative wire bond and FC’s type .PSV increased density and importantly the length of electrical connection becomes shorter thereby providing a major advantage.
TSVs used in 3D packages including 3D ICs such as image sensors a 3D package contains at least two IC layered vertically so that they occupy less space and have better connectivity. The staff chips are wired together in traditional 3D packages , this wiring is located along the edges and thus increases physical size of the package. In addition, the wiring necessitates an extra layer between the chips labeled as interposer . The SV is replaced edge based wiring by making interconnections through the body of stacked the dice advantages is that resulting device is much smaller.
Concerns in 3D ICs
- Thermal issues in 3D circuits:
thermal Effects dramatically impact interconnect and device relaibility in 2D circuits. 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. - Heat flow in 3D:
Heat Flow in 3D With multi-layer circuits , the upper layers will also generate a significant fraction of the heat. Heat increases linearly with level increase. In heat Dissipation ,all active layers will be insulated from each other by layers of dielectrics , with much lower thermal conductivity
than Si .Therefore heat dissipation in 3D circuits can accelerate many failure mechanisms.
