The routine use of aggressive OPC at advanced technology nodes, i.e., 40nm and beyond, has made photomask patterns quite complex. The high-resolution inspection of such masks often result in more false and nuisance defect detections than ever before. Traditionally, each defect is manually examined and classified by the inspection operator based on defined production criteria. The significant increase in total number of detected defects has made manual classification costly and non-manufacturable. Moreover, such manual classification is also susceptible to human judgment and hence error-prone.Luminescent's Automated Defect Classification (ADC) offers a complete and systematic approach to defect disposition and classification. The ADC engine retrieves the high resolution inspection images and uses a decision-tree flow based on the same criteria human operators use to classify a given defect. Some identification mechanisms adopted by ADC to characterize defects include defect color in transmitted and reflected images, as well as background pattern criticality based on pattern topology. In addition, defect severity is computed quantitatively in terms of its size, impacted CD error, transmission error, defective residue, and contact flux error. The final classification uses a matrix decision approach to reach the final disposition. In high volume manufacturing mask production, matching rates of greater than 90% have been achieved when compared to operator defect classifications, together with run-rates of 250+ defects classified per minute. Such automated, consistent and accurate classification scheme not only allows for faster throughput in defect review operations but also enables the use of higher inspection sensitivity and success rate for advanced mask productions with aggressive OPC features.

We demonstrate an enhancement of fluorescence emission due to bimetallic silver-gold film-induced surface plasmon wave extension. Rhodamine B (RhB) dyes were excited by the evanescent wave field produced from surface plasmon polaritons excited on metal-deposited sections along an embedded strip waveguide. Various silver-gold combinations were used to quantify for the evanescent field enhancement. The underlying silver yields better evanescent field enhancement, while the overlying gold ensures that the stability of the sensing surface is not compromised. In comparison to the conventional single gold film surface plasmon resonance (SPR) configuration, the two-layered metallic structure is capable of enhancing the surface plasmon polariton (SPP) evanescent field considerably, as verified experimentally by the ca. 4.0 times improvement in the RhB fluorescence emission. The compact waveguide structure and improved electric field probing depth can potentially be exploited for on-chip SPR--fluorescence excitation of less concentrated fluorophore-labelled biological and chemical analytes, with a capability of massively parallel processing for high throughput screening.

A novel inorganic-organic hybrid silica-zirconia solgel material, which can generate 10 microm thick film in a single spin-coating process, has been developed and employed in the fabrication of an embedded dielectric channel waveguide on a silica buffer layer of a silicon substrate. The fabricated channel waveguide core had steep ridge walls, good smoothness, and high robustness, and the novel sol synthesis enabled a precise control of the geometrical and optical parameters of the embedded dielectric channel waveguide. In the 1.55 microm telecommunication window, the fundamental modes TE(00) and TM(00) in the embedded channel waveguide had low transmission losses of 0.40 +/- 0.03 dB/cm and 0.59 +/- 0.03 dB/cm, respectively.

We demonstrate the use of surface plasmons (SPs) excited on a two-layered metallic film for enhanced particle propulsion. The extended SP field is predominantly attributed to propel particles with increased speed along metal-deposited regions. Various silver-gold combinations were used to quantify for the SP field enhancement. The underlying silver yields better SP evanescent field enhancement, while the overlying gold ensures that the stability of the sensing surface is not compromised. In comparison to the conventional single gold film SP resonance configuration for particle manipulation, the two-layered metallic structure enhances the propulsive force, as verified experimentally by ∼2.0 times increase in particle velocities.

A waveguide surface plasmon resonance (SPR) optical sensor based on wavelength modulation is presented. Strip waveguides are fabricated using MicroChem's SU-8 photoresist via UV lithography. Next, a bimetallic silver-gold film is deposited on the waveguides for exciting surface plasmon resonance. The underlying silver yields better evanescent field enhancement of the sensing surface, while the overlying gold ensures that the stability of the metallic film is not compromised. Experiments were conducted using various glucose concentrations as the analyte, and the normalized transmission output of the waveguide shows a good SPR curve for all the analytes. With a better evanescent field extension, the proposed waveguide SPR configuration extends the use of SPR, especially in bio-sensing, as longer ligands can be immobilized and bigger analytes can be monitored.

In lightwave communications, the high-power-efficiency coupling between a laser diode (LD) and a single-mode fiber (SMF) is indispensable. This paper proposes an imaginative two-microlens-array (MLA) coupling scheme whereby two revolved hyperboloid MLAs were used back-to-back between the LD and the SMF, and a coupling efficiency of 83.4% (-0.79 dB) has been achieved. The study also employs a cost-effective fabrication method, with a combination of the sample-inverted reflow technique and the soft lithography replication method, to fabricate revolved hyperboloid MLAs in inorganic-organic hybrid silica-zirconia sol-gel material. As a result, the fabricated MLAs have excellent smooth profiles and negligible discrepancies from the profiles of the ideal hyperboloid MLAs.

We present a new lithographic technique based on a hybrid photothermal process to modulate the refractive index in commercial SU-8 photoresist. Owing to a difference in cross-linking, the refractive index of unexposed SU-8 cross-linked by thermally induced polymerization is 0.0072 higher than that of SU-8 cross-linked by UV exposure and postbaking. Making use of this property, we fabricated two thick, flat-topped index-modulated diffractive optical elements (DOEs) that contain different phase distributions and measured their wavefront reconstruction. The good experimental reconstructions of the index DOEs demonstrate the potential to extend the refractive-index modulation technique for the fabrication of three-dimensional optical elements without needing a development step.

A surface plasmon resonance (SPR) optical biosensor, with a bimetallic silver–gold configuration that integrates the better evanescent field enhancement of silver, the higher resolution in the reflectivity minimum of silver, and the high chemical resistance of gold is presented. In comparison to most commercial sensors which use single gold films, the enhanced evanescent field of this double-layer configuration at the analyte–metal interface enables the monitoring of biomolecular interactions that occur further into the analyte. In addition, it is shown theoretically and demonstrated experimentally that the double-layer configuration achieves better minimum reflectivity resolution than the single gold film SPR configuration. Finally, the higher stability and better biomolecules adhesion of the proposed configuration, as weighed against a single silver film, makes it be a much better option to be employed for biosensing applications.

We present a new fabrication technique based on a two-step UV exposure lithographic process to marginally modulate the refractive index in commercial SU-8 photoresist. This technique achieves refractive index modulation as different regions undergo different thermal densification prior to UV-induced polymerization. A small refractive index contrast of 0.0008 or lower can be achieved, and this is especially useful for fabricating waveguides with a low level of propagation modes. This technique may be extended to other UV-curable epoxy photoresists and can easily be applied in the fabrication of optical elements such as optical interconnects and integrated optical sensors without the development process.