– Subwavelength (≤180nm)
With the wavelength of light used for conventional lithography being 192nm, the 180nm technology node was the first subwavelength node; bringing with it many new challenges for the layout and design engineer.
The move from LOCOS to STI isolation, introduced local stress effects to MOS devices, modelled through new parameters that required close interaction between layout and design. The proximity of devices to well edges also impacted device performance through a shift in threshold voltage.
The transition in metalisation schemes from aluminium to copper saw new challenges in that metal was no longer directly etched, but instead polished bringing about challenges with meeting density, ensuring a homogenous layout pattern that could be successfully manufactured, but also one where the performance of the layout/silicon closely correlated to functional simulations.
As technologies continued to shrink further away from the 192nm lithography limit, newer layout dependent effects were introduced, density requirements became more stringent, design rules became more complex and numerous and layout quality began to be the key ingredient in circuit performance and manufacturing yield.
Having detailed knowledge on how to address these challenges in layout is essential to ensuring the performance of the circuit is as expected when the layout is complete, and silicon is manufactured. With IC Mask Design having completed over 500 designs in this node range, our customers can have confidence when engaging with us when moving to, or working on these nodes.