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As the design rule becomes continuously smaller, the Hard OPC is being applied to pattern design in semiconductor production. Controllability of hard OPCed pattern’s quality directly affects to the performance of the device and yields of production. Critical Dimension Scanning Electron Microscopy (CD-SEM) is used to accurately confirm the Critical Dimension (CD) quality of the photomask. CD-SEM makes the pattern’s shape image by using secondary electrons information directly from the Mask surface and can measure CD values. Classically the purpose of CD-SEM measurement was to get one dimensional CD values. However it is difficult to guarantee complex hard OPCed pattern’s quality by using only one dimensional CD values because complexity of pattern design has been increased. To confirm and control the quality of hard OPCed pattern, the quality of pattern fidelity must be measured quantitatively. In order to overcome this difficulty we developed a new method to quantitatively evaluate the quality of pattern fidelity using EPE (Edge Placement Error) distance from the overlay between Target Design GDS and SEM GDS contour which is extracted from CD-SEM image. This paper represents how to define and analyze quantitatively the quality of complex hard OPCed pattern.

The 1Xnm technology node lithography is using SMO-ILT, NTD or more complex pattern. Therefore in mask defect inspection, defect verification becomes more difficult because many nuisance defects are detected in aggressive mask feature. One key Technology of mask manufacture is defect verification to use aerial image simulator or other printability simulation. AIMS™ Technology is excellent correlation for the wafer and standards tool for defect verification however it is difficult for verification over hundred numbers or more. We reported capability of defect verification based on lithography simulation with a SEM system that architecture and software is excellent correlation for simple line and space.[1] In this paper, we use a SEM system for the next generation combined with a lithography simulation tool for SMO-ILT, NTD and other complex pattern lithography. Furthermore we will use three dimension (3D) lithography simulation based on Multi Vision Metrology SEM system. Finally, we will confirm the performance of the 2D and 3D lithography simulation based on SEM system for a photomask verification.

In a Photomask manufacturing process, mask defect inspection is an increasingly important topic for 193nm optical lithography. Further extension of 193nm optical lithography to the next technology nodes, staying at a maximum numerical aperture (NA) of 1.35, pushes lithography to its utmost limits. This extension from technologies like ILT and SMO requires more complex mask patterns. In mask defect inspection, defect verification becomes more difficult because many nuisance defects are detected in aggressive mask features. One of the solutions is lithography simulation like AIMS. An issue with AIMS, however, is the low throughput of measurement, analysis etc.

Bright-field photomasks are used to print small contact holes via ArF immersion multiple patterning lithography. There are some technical difficulties when small floating dots are to be measured by SEM tools because of a false imaging shadow. However, a new scan technology of Multi Vision Metrology SEM TM E3630 presents a solution for this issue. The combination of new scan technology and the other MVM-SEM® functions can provide further extended applications with more accurate measurement results.

The detection and management of mask defects which are transferred onto wafer becomes more important day by day. As the photomask patterns becomes smaller and more complicated, using Inverse Lithography Technology (ILT) and Source Mask Optimization (SMO) with Optical Proximity Correction (OPC). To evaluate photomask quality, the current method uses aerial imaging by optical inspection tools. This technique at 1Xnm node has a resolution limit because small defects will be difficult to detect. We already reported the MEEF influence of high-end photomask using wide FOV SEM contour data of "E3630 MVM-SEM ® " and lithography simulator "TrueMask ® DS" of D2S Inc. in the prior paper [1]. In this paper we evaluate the correlation between our evaluation method and optical inspection tools as ongoing assessment. Also in order to reduce the defect classification work, we can compose the 3 Dimensional (3D) information of defects and can judge whether repairs of defects would be required. Moreover, we confirm the possibility of wafer plane CD measurement based on the combination between E3630 MVM-SEM ® and 3D lithography simulation.

To evaluate photomask quality, the current method uses spatial imaging by optical inspection tools. This technique at 1Xnm node has a resolution limit because small defects will be difficult to extract. To simulate the mask error-enhancement factor (MEEF) influence for aggressive OPC in 1Xnm node, wide FOV contour data and tone information are derived from high precision SEM images. For this purpose we have developed a new contour data extraction algorithm with sub-nanometer accuracy resulting in a wide Field of View (FOV) SEM image: (for example, more than 10um x 10um square). We evaluated MEEF influence of high-end photomask pattern using the wide FOV contour data of "E3630 MVM-SEM TM " and lithography simulator "TrueMask TM DS" of D2S, Inc. As a result, we can detect the "invisible defect" as the MEEF influence using the wide FOV contour data and lithography simulator.

As feature sizes of semiconductor device structures have continuously decreased, needs for metrology tools with high precision and excellent linearity over actual pattern sizes have been growing. And it has become important to measure not only two-dimensional (2D) but also three-dimensional (3D) shapes of patterns at 22 nm node and beyond. To meet requirements for 3D metrology capabilities, various pattern metrology tools have been developed. Among those, we assume that CDSEM metrology is the most qualified candidate in the light of its non-destructive, high throughput measurement capabilities that are expected to be extended to the much-awaited 3D metrology technology. On the basis of this supposition, we have developed the 3D metrology system, in which side wall angles and heights of photomask patterns can be measured with high accuracy through analyzing CDSEM images generated by multi-channel detectors. In this paper, we will discuss our attempts to measure 3D shapes of defect patterns on a photomask by using Advantest's "Multi Vision Metrology SEM" E3630 (MVM-SEM™ E3630).