Luminescent boosts 45-nm, 32-nm RET with inverse litho technology
By Ann Steffora Mutschler -- EDN, February 27, 2007
Lithography-enhancement tool startup Palo Alto, CA-based Luminescent Technologies Inc. today is unveiling new customer results that show its inverse lithography technology (ILT) on extremely complex 45-nm and 32-nm critical layers out-performs 65-nm optical proximity correction (OPC) capabilities.
To attain this, the company says its technology allows the production of “significantly better” pattern fidelity and the broadest possible lithography process windows on printed silicon.
ILT is an automated resolution enhancement technology (RET) that starts directly with the desired IC pattern on the wafer, explores available optical lithography space by mathematical inversion, and delivers a manufacturable mask pattern that generates the maximum design fidelity with the broadest process window. ILT fits into existing tape-out flows and leverages current-generation 193-nm lithography equipment to pattern 45- and 32-nm IC designs, the company explains.
ILT allows all critical chip layers to be reached and processed, which typically would be beyond the reach of conventional OPC solutions, as well as revealing depth-of-focus improvements and better cost-of-ownership.
Luminescent’s data comes from the evaluation of ILT by semiconductor manufacturers that are exploring ILT’s potential to optimize their cutting-edge 45-nm and 32-nm IC designs for manufacturability. The companies include foundries and IDMs (memory and logic) on multiple continents using both dry and wet immersion lithography techniques.
One customer has already installed Luminescent’s full-chip product, the Luminizer for its 32-nm development efforts, with a second order received this month for a customer’s 45-nm development initiatives, the company contends.
According to the company, customers are reporting that at the 45-nm and 32-nm nodes, ILT goes where OPC can’t reach, with the capability to solve line-end shortening problems in the poly and diffusion layers at 45 nm.
At this node, manufacturers are exploring the possibility of extending their dry steppers and delaying the move to immersion. With conventional OPC, it has been extremely difficult to print critical layers, such as poly and active, 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 solved the line-end shortening problem, easily printing 45-nm poly and diffusion layers with adequate process window.
Second, in a benchmark, the company says ILT demonstrated improved depth-of-focus (DoF) by at least 100-nm, representing an improvement of more than 30 percent over conventional solutions.
This improvement has important implications for mask manufacturability since using conventional OPC, the best DoF tends to fall below 300-nm, 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, Luminescent points out.
Third, because ILT considers mask-writing and inspection rules during the inversion calculation, the IC design is inherently optimized for manufacturability. Now, manufacturers taping out full masks are reporting mask-write time that is equal to if not better than conventional OPC, the company believes. More importantly, they are verifying that the full masks can be comprehensively inspected by current-generation mask-inspection equipment.
Finally, beyond the cost benefit of eliminating the need for script writers, customers report cost-of-ownership (CoO) advantages in the form of accelerated turnaround time. With ILT, they are consistently developing recipes in days instead of weeks, the company added.
Luminescent CEO and Applied Materials veteran David Fried concluded in a statement, “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 193-nm dry lithography instead of immersion for printing certain 45-nm critical layers. They’re also excited by the possibility of delaying the need for more advanced immersion steppers for 32-nm designs.”
For commentary on this news, see our IC design blog " Practical Chip Design ."
