Calibre Curvilinear MDP

Patterning requirements of next-generation lithographic processes and the need to keep manufacturing costs down have pushed lithographers to explore the advantages of the curvilinear masks. Multiple studies backed by the experimental results have demonstrated the lithographic advantage of curvilinear photomasks over rectilinear approximations. Manufacturability of curvilinear masks has been limited due to the architecture of the variable shaped beam writers, which made it prohibitive from both mask data preparation and mask writing perspectives. The availability of multi-beam mask writers has removed these roadblocks and brought introduction of curvilinear masks much closer to reality.

Read Curves ahead! IC manufacturing prepares for curvilinear masks to learn more about the benefits of curvilinear masks.

The Calibre Curvilinear MDP tool suite allows for seamless continuation of the data manipulations required for Resolution Enhancement Techniques (RET), such as Sub-Resolution Assist Features (SRAFs) insertion and Optical Process Correction (OPC), and Mask Process Correction (MPC) to the mask data format conversion in one batch run.

Traditionally multibeam mask writers have supported Piecewise-Linear (PWL) data in their data paths. Recently, multibeam mask writer vendors have introduced native multigon support on new generation of multibeam mask writer tools. The purpose of multigon is to represent curvilinear data with native curve format for file size compaction in the mask flows. The number of vertices used to represent the multigon data are substantially fewer than the vertices used to represent the Piecewise-Linear data, resulting in file size reduction from using native curves for curvilinear data.

The image below shows an example of PWL on the left and multigon on the right.

The Calibre Curvilinear MDP solution supports multibeam fracture flows based on multigon and is enabled with the latest multibeam formats like MBW 3.0 from IMS and MBF 2.1 from NuFlare.

• Multigon Distance Check: The multigon distance check is designed to measure the distance between spline sections on multigon layers, ensuring compliance with design constraints.
• Multigon Depth Width and Depth Width Ratio Checks: The Depth Width check ensures that the minimum width of a multigon shape is within the acceptable range, specifically when measured at a given depth range.
• Multigon Angle Check: The Angle Check evaluates the geometry of the multigon by computing the spline angle at each Point of Interest (POI) for a specified radius.
• Multigon Curvature Check: The Curvature Check is designed to assess the smoothness and bend quality of each Bezier spline section within a multigon by calculating the minimum radius of curvature along its contour.

The picture above show examples of external distance check (upper left), internal distance check (upper right), spike detection (lower left) and depth-width check (lower right).