Extreme Ultraviolet Lithography (EUVL) masks have residual stress induced by several thin films on low thermal
expansion material (LTEM) substrates. The stressed thin films finally result in convex out-of-plane displacement (OPD)
of several 100s of nm on the pattern side of the mask. Since EUVL masks are chucked on EUVL scanners differently
from on e-beam writer, the mask pattern placement errors (PPE) are necessary to be corrected for to reduce overlay
errors. In this paper, experimental results of pattern placement error correction using standard chrome on glass (COG)
plate will be discussed together with simulations. Excellent agreement with simple bending theory is obtained.
Suitability of the model to compensate for other EUVL-related PPEs due to mask non-flatness will be discussed.
It becomes increasingly important to have an integrated process for Extreme UltraViolet (EUV) mask fabrication in order to meet all the requirements for the 32 nm technology node and beyond. Intel Corporation established the EUV mask pilot line by introducing EUV-specific tool sets while capitalizing on the existing photomask technology and utilizing the standard photomask equipment and processes in 2004. Since then, significant progress has been made in
many areas including absorber film deposition, mask patterning optimization, mask blank and patterned mask defect inspection, pattern defect repair, and EUV mask reflectivity metrology. In this paper we will present the EUV mask process with the integrated solution and the results of the mask patterning process, Ta-based in-house absorber film deposition, absorber dry etch optimization, EUV mask pattern defect inspection, absorber defect repair, and mask reflectivity performance. The EUV resist wafer print using the test masks that are fabricated in the EUV mask pilot line will be discussed as well.
The introduction of extreme ultraviolet (EUV) lithography into high volume manufacturing requires the development of a new mask technology. In support of this, Intel Corporation has established a pilot line devoted to encountering and eliminating barriers to manufacturability of EUV masks. It concentrates on EUV-specific process modules and makes use of the captive standard photomask fabrication capability of Intel Corporation. The goal of the pilot line is to accelerate EUV mask development to intersect the 32nm technology node. This requires EUV mask technology to be comparable to standard photomask technology by the beginning of the silicon wafer process development phase for that technology node. The pilot line embodies Intel's strategy to lead EUV mask development in the areas of the mask patterning process, mask fabrication tools, the starting material (blanks) and the understanding of process interdependencies. The patterning process includes all steps from blank defect inspection through final pattern inspection and repair. We have specified and ordered the EUV-specific tools and most will be installed in 2004. We have worked with International Sematech and others to provide for the next generation of EUV-specific mask tools. Our process of record is run repeatedly to ensure its robustness. This primes the supply chain and collects information needed for blank improvement.
KLA-Tencor has developed a fourth-generation reticle inspection system, the KLA-Tencor 570, using DUV imaging to detect 100-nm defects on advanced OPC and PSM reticles for the 0.13 micron technology node production and 0.10 micron technology development. This system contains innovations in optics, electronics, mechanics, algorithms, and software. The DUV wavelength of the optical system improves the resolution and thus the minimum linewidth capability. A low- noise optical system generates high-quality images to improve productivity, facilitate defect classification, and reduce operator errors. The United Inspection Computer (UIC), a high-speed scalable computational engine, renders database data to create an image of the mask for die-to- database inspections. The UIC uses the new Ultra-Performance Algorithm, which provides high detection sensitivity at high speed for D:D and D:DB inspections. UPA can handle complex structures such as advanced OPC and phase shift mask. TI places no fundamental requirement on the size of OPC features. UPA classified defects automatically. The operator can select sensitivity settings independently for each defect type. Since UPA measures the CD of every feature on the reticle, it can also make total plate quality measurements for statistical process control of mask manufacturing. A new reticle handling system reduces overhead time and allows easy loading and unloading of the reticle. This system manipulates 6-inch and 230-mm reticles with and without pellicles. A flexible adapter design allows the system to mix different reticle sizes. A new data preparation system executes on a multi-processor computer with a 64-bit operating system to minimize data preparation time. This DPS architecture allows the operator to change various inspection parameters such as pixel size, alignment points, DNIR's and rotation without the need for re-prep, thereby improving productivity and flexibility. The KLA- Tencor 570 also allows optional remote Data Prep. Test results indicate that the KLA-Tencor 570 already meets its sensitivity specifications on a Verimask VT 690 in both die- to-die and die-to-database modes.
By using the hydrodynamic symmetric description, the quasi-static model of self-focusing processes has been extended to include the transient effect of nonlinear medium response. This paper presents a new operator method to study the transient nonlinear refractive index and two-photon absorption processes in which the laser pulse-width is assumed to be much shorter than or comparable to the response time of the nonlinear medium. The numerical computation uses a finite-difference implementation of a characteristic method. The asymmetrical focusing structure in full spatial and temporal coordinates are obtained. The pulse-width self- compression and the peak shifting of the wave field envelope, corresponding to the asymmetrical and anomalous broadening of the spectrum, are verified in the transient case. The influence on the self-focusing process of various parameters, including the saturation effect, is discussed.