ILT promises many benefits over old technology

Inverse Lithography Technology techniques surpass previous technical stalwarts such as optical proximity correction.

Luminescent Technologies, a provider of lithography-enhancement products to the global semiconductor industry, has unveiled new results of its most aggressive deployment of Inverse Lithography Technology (ILT) to date - this time on extremely complex 45nm and 32nm critical layers.

The patented technology is already outperforming the capabilities of state-of-the-art optical proximity correction (OPC) approaches at 65nm by producing significantly better pattern fidelity and the broadest possible lithography process windows on printed silicon.

Now it is surpassing those early success benchmarks.

The most recent results demonstrate ILT's ability to reach and process areas of all critical layers that elude the capabilities of conventional OPC solutions.

They also reveal substantial depth-of-focus improvements and new cost-of-ownership advantages.

The latest data emerges from the evaluation of ILT by a selection of semiconductor manufacturers.

The line-up includes a mix of foundries and integrated device (memory and logic) manufacturers on multiple continents using both dry and wet immersion lithography techniques; all are exploring ILT's potential to optimise their cutting-edge 45nm and 32nm IC designs for manufacturability.

One customer has already installed Luminescent's full-chip product, the Luminizer, for its 32nm development efforts.

Another Luminizer order was received this month for a customer's 45nm development initiatives.

Beyond the known advantages of ILT - superior pattern fidelity and a broader process window - customers are reporting additional findings for this new-generation RET solution at the 45 and 32nm nodes.

These include: Going where OPC can't reach: ILT has demonstrated the ability to solve line-end shortening problems in the poly and diffusion layers at 45nm.

At this node, manufacturers are exploring the possibility of extending their dry steppers and delaying the move to immersion.

With conventional OPC, printing critical layers such as poly and active has been extremely difficult due to the line-end shortening problem.

The poly layer is especially complex since the line-end space is tight, leaving no room for OPC to correct the problem.

ILT solves the line-end shortening problem, easily printing 45nm poly and diffusion layers with adequate process window.

New depth-of-focus (DoF) benchmark: ILT has demonstrated improved DoF by at least 100nm, which represents an improvement of more than 30 % over conventional solutions.

This improvement has important implications for mask manufacturability.

Using conventional OPC, the best DoF tends to fall below 300nm, which leaves a very small process margin.

The improved DoF generated by ILT expands the process margin, thereby allowing manufacturers to proceed to production with confidence using reticles with currently available CD controls.

Mask-write speed metrics and mask-inspection validation: Because ILT considers mask-writing and inspection rules during the inversion calculation, the IC design is inherently optimised for manufacturability.

Manufacturers using ILT to tape out full masks are reporting mask-write time that is equal to if not better than conventional OPC.

More importantly, they are verifying that the full masks can be comprehensively inspected by current-generation mask-inspection equipment.

Cost-of-ownership (CoO) advantages: Beyond the cost benefit of eliminating the need for script writers, customers report new CoO benefits in the form of accelerated turnaround time; with ILT, they are consistently developing recipes in days instead of weeks.

"From the outset, ILT showed tremendous promise as the most intuitive, practical and optimal mask synthesis solution", says Luminescent CEO David Fried.

"But its power as an advanced lithography enabler is even more apparent with the latest results from a selection of the world's most advanced semiconductor R and D sites".

"At the leading edge, ILT is patterning features beyond the capabilities of even the most advanced OPC while fitting into existing lithography flows".

"But beyond the technical superiority of this new-generation RET solution, manufacturers are most excited by ILT's potential to enable the use of more-economical 193nm dry lithography instead of immersion for printing certain 45nm critical layers".

"They're also excited by the possibility of delaying the need for more advanced immersion steppers for 32nm designs", added Fried.

Back to top