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Leading-edge devices are using increasingly more complex mask shapes to attain the required wafer shapes with adequate resilience to manufacturing variation. When mask shapes were largely Manhattan features where mask variation translated to wafer variation equally, determining disposition of mask discrepancy from mask design was largely a function of measuring critical dimension (CD) on mask. Today, with increasing reliance on complex rectilinear or curvilinear shapes with sub-resolution assist features on mask, determining disposition of mask discrepancy requires wafer analysis. The ultimate check – test-printing the wafer – is difficult in the mask shop. Equipment that performs aerial-image analysis is available in the mask shop, but is expensive and resource-intensive, particularly for EUV masks. Wafer aerial simulation of mask contours extracted by CD-SEM provides a practical alternative as the first filter to determine whether differences on mask are material for wafer performance.

TrueMask® WPA (wafer plane analysis) is a GPU-accelerated aerial simulation tool that integrates with mask CD-SEM systems to provide fast, highly accurate and highly repeatable CD metrology for complex and curvilinear mask shapes for both 193i and EUV masks. TrueMask® WPA enables mask shops to leverage existing CD-SEM equipment to identify mask-level CD and defect issues that will impact the wafer. TrueMask® WPA uses D2S GPU-acceleration technologies to provide aerial image simulation of 2D contours extracted by CD-SEM machines – and account for EUV mask 3D effects – at interactive speeds, and at a fraction of the cost of conventional aerial imaging techniques.


  • Enables wafer CD metrology and mask defect dispositioning for complex rectilinear and curvilinear mask shapes, including ILT shapes
  • Supports both 193i and EUV lithography simulation, including rigorous EUV mask 3D simulation
  • Speeds wafer-level CD metrology through GPU-accelerated aerial simulation
  • Provides highly repeatable wafer-level CD metrology results based on CD SEM contours
  • Integrates with industry-standard CD metrology tools for easy adoption and use
  • Reduces the load of aerial image review equipment during post-inspection mask dispositioning through more accurate defect review
  • Improves post-inspection mask dispositioning by using industry-standard, high-resolution SEM images for defect details and resolution, and by using simulated aerial image for defect printability

“Our customers’ previous experience with TrueMask® WPA has shown that the GPU-accelerated aerial simulation approach is very effective at detecting issues with optical photomasks used in 193-nm immersion (193i) lithography. This also provides significant value add to our CD-SEM tools. We look forward to seeing the same benefits extend to EUV.”

Masahiro Seyama

Senior Vice President, Nanotechnology Business Group, Advantest