Introduction to Lithography for Nanometer VLSI Manufacturing

[attachment=17240]
Optical Proximity Correction (OPC)
•Optical proximity correction (OPC) is a photolithography enhancement techniques commonly used to compensate the mask pattern for image errors due to diffraction or process effects[2].


Design for Manufacturability (DFM)
•A design methodologyincludes a set of techniquesto modify the design of ICs in order to improve:
–Functional yield, parametric yield, reliability…
•Techniques includes:
–Substituting higher yield cellswhere permitted by timing, power, and routability.
–Changing the spacingand widthof the interconnect wires, where possible
–Optimizing the amount of redundancyin internal memories.
–Substituting fault tolerant(redundant) viasin a design where possible.


Massively Parallel Mask-less Lithography (MPML2)
•E-beam lithography is capable of sub-20 nmpatterning.
•E-beam direct write technique eliminate the costof mask fabrication (~2M USD.) and correction (~1 week).
•Direct write technique is capable of patterning more complex patterns(e.g. Fresnel zone plate).
•Challenges:
–Integrate as many as possible beams into the system.
–Design an effective writing strategyto maximize system throughput.
–Electron-resist interaction(proximity effect) correction.
–Design a data transfersystem to process huge data at one time.