KLA-Tencor’s Teron 600 reticle defect inspection platform addresses mask design discontinuities at 2Xnm node

MILPITAS, USA: KLA-Tencor Corp. has introduced the Teron 600 Series reticle (mask) defect inspection systems. Addressing a major transition in mask design at the 2Xnm logic (3Xnm half-pitch memory) node, the new Teron 600 platform will introduce programmable scanner-illumination capability and offer significant improvements in sensitivity and computational lithography power over the current industry-standard platform, TeraScanTMXR.

These advances are necessary to enable development and manufacturing of the innovative reticles that distinguish the 2Xnm node.

Traditionally, mask designers have started with a mask pattern that looks like the target wafer pattern, making small adjustments to the mask features (optical proximity corrections or OPC) until the desired wafer structures are achieved. This approach begins to break down at the 2Xnm node, as a consequence of extending 193nm lithography into an extreme sub-wavelength regime.

Thus, at the 2Xnm node, computational lithography techniques such as Inverse Lithography Technology (ILT) and Source Mask Optimization (SMO) become viable. ILT typically generates a complex mask pattern with an enormous number of very small features, making the mask difficult to manufacture.

To complicate matters even further, Source Mask Optimization (SMO) involves calculating a non-uniform intensity profile for the scanner source. That profile is designed to work together with the ILT mask to deliver the optimum lithographic results on the wafer.

“The dramatic change in reticle strategy for the 2Xnm device generation has created a discontinuity in reticle defect inspection,” remarked Brian Haas, vice president and general manager of the Reticle and Photomask Inspection Division at KLA-Tencor. “The reticle features are much smaller than you would predict from a 3Xnm to 2Xnm shrink. In addition, the mask pattern is so fractured that it is no longer feasible for an engineer to look at the location of a reticle defect and decide whether it is likely to print on the wafer—and potentially cause a catastrophic yield loss in the fab.

"For the 2Xnm node, we must be able to input a custom scanner illumination profile, take into account polarization effects and the photoresist, and rigorously calculate the impact of the reticle defect on the wafer. The Teron 600 leverages KLA-Tencor’s strength in computational lithography and our experience from developing and manufacturing six generations of reticle inspection platforms. As a result it is an extremely high-resolution, low-noise reticle inspection system, equipped for the new 2Xnm challenges. It’s a big achievement for KLA-Tencor, which, we believe, will be tremendously enabling for our customers and the industry.”

The Teron 600 platform has also been designed for flexibility and extendibility. The system has successfully inspected prototype reticles created for ILT / SMO, double-patterning lithography (DPL), and EUV (masks and blanks). The system is engineered to be extendible to potential 1Xnm optical solutions.

Moreover, the Teron 600 Series can work with KLA-Tencor’s TeraScan 500 Series reticle defect inspection systems in a mix-and-match strategy, to provide a cost-effective solution for manufacturing photomask sets that include both critical and non-critical layers.