We report the development of Mask-LMC for defect printability evaluation from sub-200nm wavelength mask
inspection images. Both transmitted and reflected images are utilized, and both die-to-die and die-to-database inspection
modes are supported. The first step of the process is to recover the patterns on the mask from high resolution T and R
images by de-convolving inspection optical effects. This step uses a mask reconstruction model, which is based on
rigorous Hopkins-modeling of the inspection optics, and is pre-determined before the full mask inspection. After mask
reconstruction, wafer scanner optics and wafer resist simulations are performed on the reconstructed mask, with a wafer
lithography model. This step leverages Brion's industry-proven, hardware-accelerated LMC (Lithography
Manufacturability Check) technology1. Existing litho process models that are in use for Brion's OPC+ and verification
products may be used for this simulation. In the final step, special detectors are used to compare simulation results on the
reference and defect dice. We have developed detectors for contact CD, contact area, line and space CD, and edge
placement errors. The detection results on test and production reticles have been validated with AIMSTM.
We report the development of Mask-LMC for defect printability evaluation from sub-200nm wavelength mask
inspection images. Both transmitted and reflected images are utilized, and both die-to-die and die-to-database inspection
modes are supported. The first step of the process is to recover the patterns on the mask from high resolution T and R
images by de-convolving inspection optical effects. This step uses a mask reconstruction model, which is based on
rigorous Hopkins-modeling of the inspection optics, and is pre-determined before the full mask inspection. After mask
reconstruction, wafer scanner optics and wafer resist simulations are performed on the reconstructed mask, with a wafer
lithography model. This step leverages Brion's industry-proven, hardware-accelerated LMC (Lithography
Manufacturability Check) technology1. Existing litho process models that are in use for Brion's OPC+ and verification
products may be used for this simulation. In the final step, special detectors are used to compare simulation results on the
reference and defect dice. We have developed detectors for contact CD, contact area, line and space CD, and edge
placement errors. The detection result has been validated with AIMSTM.
This paper describes a novel technology Variable Sensitivity Detection (VSD) for de-sensing SRAF nuisance
defects in a mask inspection system. The point of our approach is to search the nearest thin-line to each defect
candidate and estimate the line-width with transmitted and reflected images. The dependence of transmitted
and reflected image contract on line-width is calculated with a rigorous model. This technology de-senses lineend
shortening and edge roughness of SRAF patterns without compromising sensitivity to main features. Total
counts of SRAF nuisance detection were drastically reduced. The VSD technology was implemented to a platform
of Nuflare NPI-5000PLUS.
In this paper we present the method that NuFlare photomask inspection systems can use to strongly reduce
pseudo detections by use of TK-CMI software. The NuFlare inspection system is capable to detect the
smallest defects in the 45 and 32-nm nodes and has recently been introduced to production. It links up with
a compute cluster with Takumi's Criticality-Marker Information software (TK-CMI). TK-CMI quickly analyzes
the ~200GB post-OPC layout or multi-layer pre-OPC layout and assigns various types of criticality regions.
The basic set of criticalities is made to address the challenges that typical maskmakers experience. The TKCMI
system also supports design-intent-based criticalities. The NuFlare inspection system uses this full-mask
criticality information and generates flexible inspection recipes that inspect low-criticality areas with relaxed
sensitivity resulting in reduction of pseudo detections in such regions.
The lithography potential of an ArF (193nm) laser exposure tool with high numerical aperture (NA) will expand
its lithography potential to 65nm node production and even beyond. Consequently, a mask inspection system with a light
source, whose wavelength is nearly equal to 193nm, is required so as to detect defects of the masks using resolution
enhancement technology (RET). Wavelength consistency between exposure tool and mask inspection tool is strongly
required in the field of mask fabrication to obtain high defect inspection sensitivity. Therefore, a novel high-resolution
mask inspection platform using DUV wavelength has been developed, which works at 198.5nm. This system has
transmission and reflection inspection mode, and throughput using 70nm pixel size were designed within 2 hours per
mask. In this paper, transmitted and reflected light image acquisition system and high accuracy focus detection optics are
presented.
We have developed a mask inspection system using 199nm inspection light wavelength. This system performs
transmission and reflection inspection processes concurrently within two hours per plate. By the evaluation result of
mask images and inspection sensitivity, it is confirmed that the 199nm inspection system has the advantage over the
system using 257nm and has the possibility corresponding to next generation mask inspection. Furthermore, advanced
die-to-database (D-DB) inspection, which can generate high-fidelity of a reference image based on the CAD data for
alternating phase shift mask (PSM) or tri-tone, is required for next generation inspection system, too. Therefore, a
reference image generation method using two-layer CAD data has been developed. In this paper, the effectiveness of
this method is described.
The usage of ArF immersion lithography for hp 65nm node and beyond leads to the increase of mask error enhancement factor in the exposure process. Wavelength of inspection tool is required to consistent with wavelength of lithography tool. Wavelength consistency becomes more important by the introduction of phase shift mask such as Tri-tone mask and alternating phase shift mask. Therefore, mask inspection system, whose inspection light wavelength is 199nm, has been developed. This system has transmission and reflection inspection mode, and throughput, using 70 nm pixel size, were designed within 2hours per mask. The experimental results show expected advantages for Die-to-Die and Die-to-Database inspection compared with the system using 257nm inspection optics. Shorter wavelength effect makes transmission inspection sensitivity increase, and realizes 40nm size particle inspection. As for the phase shift mask, the difference of gray value between the area with phase defect and without phase defect was clear relatively. In this paper, specifications and design, experimental results are described.
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